Fingerprint detection device and display device

ABSTRACT

A fingerprint detection device includes: a substrate having a first surface and a second surface on an opposite side of the first surface, the first surface serving as a detection surface configured to detect unevenness of an object in contact or in proximity; a detection electrode provided on the second surface side of the substrate and configured to detect unevenness of a finger in contact or in proximity on the basis of an electrostatic capacitance change; and a drive circuit provided on the second surface side of the substrate and configured to supply a drive signal to the detection electrode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of application Ser. No. 15/412,793,filed Jan. 23, 2017, and claims priority from Japanese Application No.2016-013514, filed on Jan. 27, 2016; Japanese Application No.2016-013515, filed on Jan. 27, 2016; and Japanese Application No.2017-006159 filed on Jan. 17, 2017, the contents of which areincorporated by reference herein in its entirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a fingerprint detection device and adisplay device.

2. Description of the Related Art

Some electronic apparatuses including a display device such as a liquidcrystal display device are provided with a fingerprint detection device.The fingerprint detection device detects the unevenness of a fingerprintof a finger in contact therewith to detect the shape of the fingerprint.Detection results of a fingerprint sensor are used for personalauthentication and other purposes. For example, in a fingerprintdetection device disclosed in Japanese Patent Application Laid-openPublication No. 2002-245443 (JP-A-2002-245443), detection electrodes forfingerprint detection, a drive circuit, and a detection circuit areprovided on an insulating substrate.

In some electronic apparatuses having a fingerprint detection devicemounted thereon, a functional surface such as a display function ofdisplaying images is provided on the opposite side of a detectionsurface for detecting fingerprints. In JP-A-2002-245443, a detectionelectrode is provided above a switching element, and hence a surface onthe transparent substrate side cannot be used as the detection surfacefor fingerprint detection, which may limit the arrangement of thedetection surface.

SUMMARY

According to an aspect, a fingerprint detection device includes asubstrate having a first surface and a second surface on an oppositeside of the first surface, the first surface serving as a detectionsurface configured to detect unevenness of an object in contact or inproximity, a detection electrode provided on the second surface side ofthe substrate and configured to detect unevenness of a finger in contactor in proximity on the basis of an electrostatic capacitance change, anda drive circuit provided on the second surface side of the substrate andconfigured to supply a drive signal to the detection electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a configuration example of afingerprint detection device according to a first embodiment;

FIG. 2 is an explanatory diagram for describing the fundamentalprinciple of self-capacitance fingerprint detection, illustrating thestate in which a finger is not in contact or in proximity with thefingerprint detection device;

FIG. 3 is an explanatory diagram for describing the fundamentalprinciple of self-capacitance fingerprint detection, illustrating thestate in which a finger is in contact or in proximity with thefingerprint detection device;

FIG. 4 is an explanatory diagram illustrating an example of anequivalent circuit for the self-capacitance fingerprint detection;

FIG. 5 is a diagram illustrating an example of waveforms of a drivesignal and a detection signal for the self-capacitance fingerprintdetection;

FIG. 6 is a schematic diagram illustrating a mechanism of thefingerprint detection by a detection unit;

FIG. 7 is a plan view of the fingerprint detection device according tothe first embodiment;

FIG. 8 is a sectional view illustrating a schematic sectional structureof the fingerprint detection device according to the first embodiment;

FIG. 9 is a plan view schematically illustrating the arrangement ofdetection electrodes and switching elements;

FIG. 10 is an enlarged plan view of the detection electrode;

FIG. 11 is a sectional view taken along the line XI-XI′ in FIG. 10;

FIG. 12 is a timing waveform diagram of the fingerprint detection deviceaccording to the first embodiment;

FIG. 13 is an enlarged plan view of a detection electrode according to asecond embodiment;

FIG. 14 is a sectional view taken along the line XIV-XIV′ in FIG. 13;

FIG. 15 is an enlarged plan view of a detection electrode according to amodification of the second embodiment;

FIG. 16 is an enlarged plan view of a detection electrode according to athird embodiment;

FIG. 17 is a sectional view taken along the line XVII-XVII′ in FIG. 16;

FIG. 18 is an enlarged plan view of a detection electrode according to afourth embodiment;

FIG. 19 is a sectional view taken along the line XIX-XIX′ in FIG. 18;

FIG. 20 is a block diagram illustrating a configuration example of adisplay device according to a fifth embodiment;

FIG. 21 is a sectional view illustrating a schematic sectional structureof the display device according to the fifth embodiment;

FIG. 22 is a circuit diagram illustrating fundamental pixel circuits;

FIG. 23 is a plan view illustrating a planar structure of the displaydevice according to the fifth embodiment;

FIG. 24 is an enlarged plan view of a portion corresponding to onesubpixel;

FIG. 25 is a sectional view taken along the line XXV-XXV′ in FIG. 24;

FIG. 26 is a sectional view taken along the line XXVI-XXVI′ in FIG. 24;

FIG. 27 is a timing waveform diagram illustrating an operation exampleof fingerprint detection operation;

FIG. 28 is an enlarged plan view of a portion corresponding to onesubpixel in a display device according to a sixth embodiment;

FIG. 29 is a sectional view taken along the line XXIX-XXIX′ in FIG. 28;

FIG. 30 is a sectional view illustrating a sectional structure of adisplay device according to a seventh embodiment;

FIG. 31 is a sectional view illustrating a sectional structure of adisplay device according to a modification of the seventh embodiment;

FIG. 32 is a schematic sectional view schematically illustrating asectional structure of a fingerprint detection device according to aneighth embodiment;

FIG. 33 is a plan view illustrating a planar structure of thefingerprint detection device according to the eighth embodiment;

FIG. 34 is an enlarged plan view of a first detection electrode and asecond detection electrode;

FIG. 35 is a sectional view taken along the line XXXV-XXXV′ in FIG. 34;

FIG. 36 is a sectional view taken along the line XXXVI-XXXVI′ in FIG.34;

FIG. 37 is a timing waveform diagram illustrating an operation exampleof the fingerprint detection device according to the eighth embodiment;

FIG. 38 is an enlarged plan view of a first detection electrode and asecond detection electrode in a fingerprint detection device accordingto a first modification of the eighth embodiment;

FIG. 39 is an enlarged plan view of a first detection electrode and asecond detection electrode in a fingerprint detection device accordingto a second modification of the eighth embodiment;

FIG. 40 is a schematic sectional view schematically illustrating asectional structure of a display apparatus according to a ninthembodiment; and

FIG. 41 is a perspective view of the display apparatus according to theninth embodiment, for describing the state in which fingerprintdetection operation is used.

DETAILED DESCRIPTION

Modes for carrying out the present invention (embodiments) are describedin detail with reference to the accompanying drawings. The presentinvention is not intended to be limited by what is described in thefollowing embodiments. Constituent elements described below encompasselements that may readily occur to those skilled in the art andsubstantially identical elements. The constituent elements describedbelow can be combined as appropriate. The present disclosure is merelyillustrative, and it should be understood that appropriate changeskeeping the gist of the present invention that may readily occur tothose skilled in the art are encompassed in the scope of the presentinvention. For a clearer description, some drawings schematicallyillustrate the width, thickness, shape, and the like of each portion indimensions different from those in practice, but the drawings are merelyillustrative and are not intended to limit the interpretation of thepresent invention. In the present specification and drawings, the sameelements as those described with reference to the drawings alreadymentioned are denoted by the same reference symbols and detaileddescriptions thereof are sometimes omitted as appropriate.

First Embodiment

FIG. 1 is a block diagram illustrating a configuration example of afingerprint detection device according to a first embodiment. Asillustrated in FIG. 1, a fingerprint detection device 1 includes afingerprint detection unit 30, a control unit 11, a gate driver 12, adetection electrode driver 14, and a detection unit 40.

As described later, the fingerprint detection unit 30 detectsfingerprints by sequentially scanning detection lines one by one inaccordance with a scanning signal Vscan supplied from the gate driver12. The fingerprint detection unit 30 detects fingerprints by detectingthe unevenness of an object in contact or in proximity on the basis ofthe principle of self-capacitance detection.

The control unit 11 is a circuit configured to supply control signals tothe gate driver 12, the detection electrode driver 14 respectively, andthe detection unit 40 and control the gate driver 12, the detectionelectrode driver 14, and the detection unit 40 to operate insynchronization with one another.

The gate driver 12 has a function of sequentially selecting detectionelectrode blocks one by one that are subjected to detection driving bythe fingerprint detection unit 30 on the basis of the control signalsupplied from the control unit 11.

The detection electrode driver 14 is a circuit configured to supply adrive signal Vf to a detection electrode 25 subjected to detectiondriving by the fingerprint detection unit 30 on the basis of the controlsignal supplied from the control unit 11.

The detection unit 40 is a circuit configured to detect thepresence/absence of a finger in contact or in proximity, with finepitches on the basis of the control signal supplied from the controlunit 11 and a detection signal Vdet supplied from the fingerprintdetection unit 30. For example, the detection unit 40 includes adetection signal amplification unit 42, an A/D conversion unit 43, asignal processing unit 44, a coordinate extraction unit 45, and acombining unit 46. A detection timing control unit 47 controls thedetection signal amplification unit 42, the A/D conversion unit 43, thesignal processing unit 44, the coordinate extraction unit 45, and thecombining unit 46 so that these units operate in synchronization withone another on the basis of the control signal supplied from the controlunit 11.

The detection signal amplification unit 42 amplifies the detectionsignal Vdet supplied from the fingerprint detection unit 30. Thedetection signal amplification unit 42 may include an analog low passfilter (LPF), which is an analog low band pass filter. The analog LPFremoves high frequency components (noise components) included in thedetection signal Vdet and outputs the resultant signal.

The A/D conversion unit 43 samples, at timings synchronized with thedrive signals Vf, each of the analog signals output from the detectionsignal amplification unit 42 and converts the sampled signals intodigital signals.

The signal processing unit 44 includes a digital filter. The digitalfilter reduces frequency components (noise components) included in theoutput signal from the A/D conversion unit 43 other than the frequencyat which the drive signal Vf is sampled. The signal processing unit 44is a logic circuit configured to detect the presence/absence of a fingerin contact or in proximity with the fingerprint detection unit 30 on thebasis of the output signal from the A/D conversion unit 43.

The coordinate extraction unit 45 is a logic circuit configured todetermine detection coordinates at which the finger in contact or inproximity is detected by the signal processing unit 44. The coordinateextraction unit 45 outputs the detection coordinates to the combiningunit 46. The combining unit 46 combines the detection signals Vdetoutput from the respective detection electrodes 25 in the fingerprintdetection unit 30 to generate two-dimensional information representingthe shape of an object in contact or in proximity.

As described above, the fingerprint detection unit 30 operates on thebasis of the fundamental principle of capacitance fingerprint detection.Referring to FIGS. 2 to FIG. 5, the fundamental principle ofself-capacitance fingerprint detection is now described. FIG. 2 is anexplanatory diagram for describing the fundamental principle ofself-capacitance fingerprint detection, illustrating the state in whicha finger is not in contact or in proximity with the fingerprintdetection device. FIG. 3 is an explanatory diagram for describing thefundamental principle of self-capacitance fingerprint detection,illustrating the state in which a finger is in contact or in proximitywith the fingerprint detection device. FIG. 4 is an explanatory diagramillustrating an example of an equivalent circuit for theself-capacitance fingerprint detection. FIG. 5 is a diagram illustratingan example of waveforms of a drive signal and a detection signal for theself-capacitance fingerprint detection. In the following, the state inwhich a finger is in contact or in proximity with a detection electrodeor the like is referred to as “touch state”.

The left diagram in FIG. 2 illustrates an untouched state in which apower source Vdd and a detection electrode E1 are coupled together by aswitch SW1 and the detection electrode E1 is not coupled to a capacitorCcr by a switch SW2. In this state, a capacitance Cx1 of the detectionelectrode E1 is charged. The right diagram in FIG. 2 illustrates thestate in which the coupling between the power source Vdd and thedetection electrode E1 is turned off by the switch SW1 and the detectionelectrode E1 and the capacitor Ccr are coupled together by the switchSW2. In this state, electric charges of the capacitance Cx1 aredischarged through the capacitor Ccr.

The left diagram in FIG. 3 illustrates the touch state in which thepower source Vdd and the detection electrode E1 are coupled together bythe switch SW1 and the detection electrode E1 is not coupled to thecapacitor Ccr by the switch SW2. In this state, not only the capacitanceCx1 of the detection electrode E1 but also a capacitance Cx2 generatedby a finger in proximity with the detection electrode E1 is charged. Theright diagram in FIG. 3 illustrates the state in which the power sourceVdd and the detection electrode E1 are turned off by the switch SW1 andthe detection electrode E1 and the capacitor Ccr are coupled together bythe switch SW2. In this state, the electric charges of the capacitanceCx1 and electric charges of the capacitance Cx2 are discharged throughthe capacitor Ccr.

Voltage change characteristics of the capacitor Ccr during the discharge(touch state) illustrated in the right diagram in FIG. 3 are obviouslydifferent from voltage change characteristics of the capacitor Ccrduring the discharge (untouched state) illustrated in the right diagramin FIG. 2 because the capacitance Cx2 is present. Thus, in theself-capacitance method, the fact that the voltage changecharacteristics of the capacitor Ccr differ depending on thepresence/absence of the capacitance Cx2 is used to determine thepresence/absence of a touch.

Specifically, an AC square wave Sg (refer to FIG. 5) having apredetermined frequency (for example, about several kHz to severalhundreds of kHz) is applied to the detection electrode E1. A voltagedetector DET illustrated in FIG. 4 converts a fluctuation in currentcorresponding to the AC square wave Sg into a fluctuation in voltage(waveforms V₃ and V₄).

As described above, the detection electrode E1 is configured to bedecoupled from the capacitor Ccr by the switch SW1 and the switch SW2.In FIG. 5, the AC square wave Sg raises the voltage level correspondingto a voltage V₀ at the timing of time T₀₁. At this time, the switch SW1is on and the switch SW2 is off. Accordingly, the voltage of thedetection electrode E1 also increases to the voltage V₀. Next, theswitch SW1 is turned off before the timing of time T₁₁. At this time,the detection electrode E1 is in a floating state, but the potential ofthe detection electrode E1 is maintained at V₀ due to the capacitanceCx1 of the detection electrode E1 (refer to FIG. 2) or the capacitanceobtained by adding the capacitance Cx2 of a finger generated by a touchto the capacitance Cx1 of the detection electrode E1 (Cx1+Cx2, see FIG.3). A switch SW3 is turned on before the timing of time T₁₁ and turnedoff after the lapse of a predetermined period to reset the voltagedetector DET. This reset operation causes an output voltage of thevoltage detector DET to be a voltage substantially equal to Vref.

Subsequently, when the switch SW2 is turned on at the timing of timeT₁₁, an inverting input part of the voltage detector DET has the voltageV0 of the detection electrode E1, and after that, the voltage of theinverting input part of the voltage detector DET decreases to thereference voltage Vref in accordance with a time constant of thecapacitance Cx1 (or Cx1+Cx2) of the detection electrode E1 and acapacitance C5 in the voltage detector DET. At this time, the electriccharges stored in the capacitance Cx1 (or Cx1+Cx2) of the detectionelectrode E1 are transferred to the capacitance C5 in the voltagedetector DET, and hence the output of the voltage detector DET increases(Vdet). When a finger or the like is not in proximity with the detectionelectrode E1, the output (Vdet) of the voltage detector DET exhibits thewaveform V₃ indicated by solid line, and Vdet=Cx1×V0/C5 is established.When the capacitance due to the influence of a finger or the like isadded, the output (Vdet) of the voltage detector DET exhibits thewaveform V₄ indicated by dotted line, and Vdet=(Cx1+Cx2)×V0/C5 isestablished.

After that, the switch SW2 is turned off and the switch SW1 and theswitch SW3 are turned on at the timing of time T₃₁ at which the electriccharges of the capacitance Cx1 (or Cx1+Cx2) of the detection electrodeE1 have been sufficiently transferred to the capacitance C5, therebysetting the potential of the detection electrode E1 to Low level, whichis the same potential as the AC square wave Sg and resetting the voltagedetector DET. The timing of turning on the switch SW1 may be any timingafter the switch SW2 is turned off and before time T₀₂. The timing ofresetting the voltage detector DET may be any timing after the switchSW2 is turned off and before time T₁₂. The operation described above isrepeated at a predetermined frequency (for example, about several kHz toseveral hundreds of kHz). The presence/absence of a touch can bemeasured on the basis of the absolute value |ΔV| of the differencebetween the waveform V₃ and the waveform V₄. As illustrated in FIG. 5,the potential of the detection electrode E1 exhibits a waveform V₁ whena finger or the like is not in proximity, and exhibits a waveform V₂when the capacitance Cx2 due to the influence of a finger or the like isadded.

FIG. 6 is a schematic diagram illustrating a mechanism of thefingerprint detection by the detection unit 40. The combining unit 46combines detection signals Vdet from a plurality of detection electrodesE1 to generate two-dimensional information representing the shape of anobject in touch with the detection electrodes E1. Specifically, forexample, when an external object in proximity having unevenness on itssurface (for example, a human finger) contacts the fingerprint detectionunit 30 (refer to FIG. 1), a difference in detection intensity occurs inaccordance with the unevenness because the distance between the objectand the fingerprint detection unit 30 differs depending on theunevenness. The combining unit 46 generates a two-dimensional imagerepresenting the difference in detection intensity as color contrast(for example, grayscale). An output Vout of the detection unit 40including the combining unit 46 is, for example, an output of thetwo-dimensional information described above.

For easy understanding, FIG. 6 exemplifies two-gradation detectionrepresenting only the presence/absence of a finger in contact or inproximity. In practice, detection results in each block can berepresented as multi-gradation. In FIG. 6, the detected external objectin proximity is an object having double-circular unevenness. In the casewhere an external object in proximity is a human finger, when the fingertouches the fingerprint detection unit 30 with a fingerprint part, afingerprint appears as two-dimensional information. The function of thecombining unit 46 may be implemented in units other than the detectionunit 40. For example, the output Vout of the detection unit 40 may beset to the output of the coordinate extraction unit 45, and an externalconfiguration may generate two-dimensional information on the basis ofthe output Vout. The configuration related to the generation oftwo-dimensional information may be hardware such as a circuit, or may beimplemented by what is called software processing.

Next, a configuration example of the fingerprint detection device 1 isdescribed in detail. FIG. 7 is a plan view of the fingerprint detectiondevice according to the first embodiment. FIG. 8 is a sectional viewillustrating a schematic sectional structure of the fingerprintdetection device according to the first embodiment. FIG. 8 illustratesthe section of the fingerprint detection device 1 that is incorporatedinto a casing 101 of an external electronic apparatus. The fingerprintdetection device 1 is incorporated into an electronic apparatusincluding a display device (not illustrated) such as a liquid crystaldisplay device, and is disposed on the rear surface side of a displaysurface of the liquid crystal display device on which an image isdisplayed. The fingerprint detection device 1 is incorporated in anopening part of the casing 101. When a finger is brought into contactwith a portion where the fingerprint detection device 1 is provided, afingerprint is detected. In the following, detecting surface unevennessof a human finger is hereinafter referred to as “fingerprint detection”.

As illustrated in FIG. 7 and FIG. 8, the fingerprint detection device 1includes a substrate 21 and a plurality of detection electrodes 25provided on the substrate 21. The substrate 21 has a first surface 21 aand a second surface 21 b on the opposite side of the first surface 21a. The first surface 21 a of the substrate 21 is a detection surface fordetecting the unevenness of a finger in contact or in proximity with thefirst surface 21 a. As illustrated in FIG. 8, the first surface 21 a ofthe substrate 21 may be provided with a protective layer 29 forprotecting the substrate 21, and the second surface 21 b of thesubstrate 21 may be provided with a protective layer 56. A control IC 19and a flexible substrate 36 are further provided on the second surface21 b of the substrate 21. The control IC 19 has mounted thereon thecontrol unit 11 and the detection unit 40 illustrated in FIG. 1. Theoutput Vout from the detection unit 40 is output to an external circuitthrough the flexible substrate 36. When the first surface 21 a of thesubstrate 21 is covered with the protective layer 29, the surface of theprotective layer 29 can be defined as a detection surface. In otherwords, in the fingerprint detection device 1, a surface that a fingerdirectly contacts may be a detection surface. In the following, afingerprint of a finger in contact with the detection surface issometimes referred to simply as “fingerprint”.

A glass substrate can be used as the substrate 21. For example, the useof toughened glass enables the substrate 21 to be thinned while thestrength is maintained. Examples of toughened glass that can be usedinclude, but are not limited to, chemically toughened glass in which acompressive stress layer is formed on the surface by exchanging sodium(Na) ions on the surface of glass with potassium (K) ions having largerion radius, toughened glass in which a compressive stress layer isformed on the surface by supplying air to a heated glass substrate forquenching, for example. The substrate 21 may be six-sided toughenedglass.

The detection electrodes 25 are provided on the second surface 21 b ofthe substrate 21. As illustrated in FIG. 7, the detection electrodes 25each have a rectangular shape and are arranged in a matrix pattern. Forexample, the detection electrodes 25 are arranged in the row directionwith a pitch of 50 μm, and the detection electrodes 25 are arranged inthe column direction with a pitch of 50 μm. The arrangement pitch in therow direction and the arrangement pitch in the column direction may bedifferent from each other. The detection electrodes 25 arranged in amatrix pattern constitute the fingerprint detection unit 30. Thedetection electrode 25 corresponds to the detection electrode E1 in thefundamental principle of self-capacitance fingerprint detectiondescribed above, and is capable of detecting a fingerprint in contactwith the detection surface on the basis of an electrostatic capacitancechange in the detection electrode 25. A metal material such asmolybdenum (Mo) can be used for the detection electrode 25. A metalmaterial of at least one of aluminum (Al), copper (Cu), silver (Ag), oran alloy thereof may be used for the detection electrode 25.

The region where the detection electrodes 25 are arranged is a detectionregion 21 c where a fingerprint can be detected, and the outside of thedetection region 21 c is a frame region 21 d. The control IC 19 and theflexible substrate 36 are provided in the frame region 21 d. The gatedriver 12 and the detection electrode driver 14 may be further providedin the frame region 21 d of the second surface 21 b.

As illustrated in FIG. 8, the frame region 21 d of the substrate 21 isfixed to a fixing part 101 a of the casing 101 (refer to FIG. 8). Thefirst surface 21 a of the substrate 21 is exposed from the opening partin the casing 101. In this case, the detection region 21 c is disposedto overlap with the opening part. When a finger of an operator contactsthe detection surface exposed from the opening part, the fingerprintdetection device 1 can detect a fingerprint. As described above, in thefingerprint detection device 1 according to the first embodiment, thefirst surface 21 a is a detection surface, and the detection electrodes25, the control IC 19, and the flexible substrate 36 are provided on thesecond surface 21 b on the opposite side of the detection surface. Thus,the fixation of the substrate 21 to the casing 101 is less restricted bythe bump of the control IC 19 and the flexible substrate 36.Specifically, the casing 101 is opposed to the flat plate-shaped firstsurface 21 a side, which simplifies the structure around the openingpart in the casing 101 to facilitate the processing of the casing 101and the mounting of the fingerprint detection device 1 to the casing101. The flexible substrate 36, the control IC 19, and other componentsare not placed on the first surface 21 a side, but there is only a flatdetection surface. Thus, a space for allowing the flexible substrate 36to turn around or a space for placing the control IC 19 is not requiredto be formed between the substrate 21 and the casing 101, and thedetection surface can be provided at a position that is closer to theouter surface of the casing 101 by the spaces. Consequently, thedetection surface can be provided at a position that is closer to theouter surface of the casing 101 with respect to the inner surface of thecasing 101, and the difference in bump between the outer surface of thecasing 101 and the detection surface can be reduced. The control IC 19and the flexible substrate 36 are provided on the second surface 21 b,and hence no conductor such as a wire is present on the first surface 21a side with respect to the detection electrode 25. Consequently,detection errors and the deterioration in detection sensitivity can besuppressed.

Next, the structure of the detection electrodes 25 is described indetail. FIG. 9 is a plan view schematically illustrating the arrangementof the detection electrodes and switching elements. As illustrated inFIG. 9, the detection electrodes 25, switching elements Tr, gate linesGCL, and data lines SGL are provided on the second surface 21 b of thesubstrate 21. The gate lines GCL and the data lines SGL are wired so asto intersect with each other. The direction parallel to the direction inwhich the gate lines GCL extend is the row direction, and the directionparallel to the direction in which the data lines SGL extend is thecolumn direction. The gate line GCL is provided along the row direction,and the gate lines GCL are arranged in the column direction. The dataline SGL is provided along the column direction, and the data lines SGLare arranged in the row direction. Each detection electrode 25 isdisposed in a region surrounded by the gate lines GCL and the data linesSGL. The detection electrodes 25 each have a rectangular shape, butwithout being limited thereto, the detection electrodes 25 may haveanother shape such as a rhombic shape and a polygonal shape.

Each of the switching elements Tr is provided near the position at whichthe gate line GCL and the data line SGL intersect with each other. Theswitching element Tr is disposed to correspond to each detectionelectrode 25. The switching element Tr is formed of a thin filmtransistor. In the present example, the switching element Tr is formedof an n-channel metal oxide semiconductor (MOS) thin film transistor(TFT).

The gate driver 12 illustrated in FIG. 1 sequentially selects the gatelines GCL. The gate driver 12 supplies the scanning signal Vscan to theswitching element Tr through the selected gate line GCL. In this manner,the gate driver 12 selects one line (one horizontal line) of thedetection electrodes 25 as a detection electrode block 25A to bedetected. The detection electrode block 25A includes a plurality ofdetection electrodes 25 arranged in the row direction. The detectionelectrode driver 14 supplies the drive signal Vf to each detectionelectrode 25 in the detection electrode block 25A through the data lineSGL. The detection unit 40 receives a detection signal Vdetcorresponding to an electrostatic capacitance change in each detectionelectrode 25 in accordance with the fundamental principle ofself-capacitance fingerprint detection described above. In this manner,a fingerprint of a finger in touch with the detection surface isdetected.

As illustrated in FIG. 9, a conductive layer 51 is provided so as tocover the detection electrode 25. The gate line GCL is provided alongone side of the detection electrode 25, and a conductive first wire ASL1is provided between the gate line GCL and the one side of the detectionelectrode 25. A second wire ASL2 is provided on the opposite side of thefirst wire ASL1 across the detection electrode 25. The first wire ASL1and the second wire ASL2 are provided along the gate lines GCL. Thefirst wire ASL1 and the second wire ASL2 are provided to correspond tothe detection electrode block 25A, and are continuous in adjacent to thedetection electrodes 25. A third wire ASL3 is further provided along thefirst wire ASL1 and the second wire ASL2. The third wire ASL3 isprovided along the gate line GCL so as to overlap with the gate lineGCL.

Aluminum (Al) or an aluminum alloy is used for the gate line GCL and thedata line SGL. A metal material such as molybdenum (Mo) can be used forthe conductive layer 51, the first wire ASL1, the second wire ASL2, andthe third wire ASL3. A metal material of at least one of aluminum (Al),copper (Cu), silver (Ag), or an alloy thereof may also be used.

As described above, the gate line GCL is supplied with the signal(scanning signal Vscan) different from the signal supplied to the dataline SGL and the detection electrode 25. Thus, a parasitic capacitancebetween the gate line GCL and the detection electrode 25 and a parasiticcapacitance between the gate line GCL and the data line SGL canincrease. When the parasitic capacitance increases, the electrostaticcapacitance change caused by a finger in contact or in proximity isrelatively reduced, and detection sensitivity can deteriorate.

In the first embodiment, the detection electrode driver 14 supplies theconductive layer 51, the first wire ASL1, the second wire ASL2, and thethird wire ASL3 with a signal Vsg1 that is synchronized with the drivesignal Vf and has the same waveform as the drive signal Vf. Thus, theparasitic capacitance between the detection electrode 25 and the gateline GCL is reduced. Consequently, detection errors and thedeterioration in detection sensitivity are suppressed. A drive circuitthat is not provided in the detection electrode driver 14 may beprovided as appropriate to supply the signal Vsg1.

Next, the configuration of the detection electrode 25, each wire, andthe conductive layer is described in detail. FIG. 10 is an enlarged planview of the detection electrode. FIG. 11 is a sectional view taken alongthe line XI-XI′ in FIG. 10. In FIG. 11, the up-down direction isopposite from that in FIG. 8, that is, the first surface 21 a of thesubstrate 21, which is formed as the detection surface, is illustratedas facing downward.

As illustrated in FIG. 10 and FIG. 11, the switching element Tr includesa semiconductor layer 61, a source electrode 62, a drain electrode 63,and a gate electrode 64. As the material for the semiconductor layer 61,a well-known material such as polysilicon and oxide semiconductor can beused.

The semiconductor layer 61 is electrically coupled to the data line SGLvia a contact hole H1. A part of the data line SGL that overlaps withthe semiconductor layer 61 functions as the source electrode 62. Thesemiconductor layer 61 is bent so as to intersect with the gate line GCLa plurality of times in a plan view. A part of the gate line GCL thatoverlaps with the semiconductor layer 61 functions as the gate electrode64. The semiconductor layer 61 is electrically coupled to the drainelectrode 63 via a contact hole H2. The drain electrode 63 is providedto extend from the side of the gate line GCL to the position overlappingwith the detection electrode 25 while intersecting with the first wireASL1. The drain electrode 63 is electrically coupled to the detectionelectrode 25 via a contact hole H3 at the position overlapping with thedetection electrode 25.

As illustrated in FIG. 11, the third wire ASL3 and the detectionelectrode 25 are provided on the second surface 21 b of the substrate21. An insulating layer 58 a is provided on the third wire ASL3 and thedetection electrode 25. The semiconductor layer 61 is provided on theinsulating layer 58 a. An insulating layer 58 b is provided on thesemiconductor layer 61, and the gate line GCL and the first wire ASL1are provided on the insulating layer 58 b. An insulating layer 58 c isprovided on the gate line GCL and the first wire ASL1, and the drainelectrode 63, the data line SGL, and the conductive layer 51 areprovided on the insulating layer 58 c. A planarization layer 59 isprovided on the drain electrode 63, the data line SGL, and theconductive layer 51, and a protective layer 77 is provided on theplanarization layer 59. The second wire ASL2 (not illustrated in FIG.11) is provided in the same layer as the gate line GCL and the firstwire ASL1. Although omitted in FIG. 11, when the protective layer 29(refer to FIG. 8) is provided, a fingerprint of a finger in contact withthe protective layer 29 is detected by the fingerprint detection device1.

In the first embodiment, the detection electrode 25 is provided closerto the second surface 21 b of the substrate 21 than the gate line GCLis. The insulating layers 58 a and 58 b are provided between thedetection electrode 25 and the gate line GCL. In other words, thedetection electrode 25 is closer to the first surface 21 a serving asthe detection surface than the switching element Tr is. Only thesubstrate 21 or the substrate 21 and the protective layer 29 areprovided between the detection electrode 25 and the detection surface.Thus, no conductor such as wire is present on the first surface 21 aside with respect to the detection electrode 25, and the distancebetween a finger in contact with the detection surface and the detectionelectrode 25 is reduced. Consequently, the deterioration in detectionsensitivity can be suppressed.

As illustrated in FIG. 10, the third wire ASL3 is provided with a tabportion ASL3 a at the position overlapping with the conductive layer 51.The tab portion ASL3 a intersects with the first wire ASL1, and isdisposed with a gap from the detection electrode 25. The tab portionASL3 a is electrically coupled to the conductive layer 51 via a contacthole H4. The conductive layer 51 is provided to overlap with thedetection electrode 25 and the first wire ASL1, and is electricallycoupled to the first wire ASL1 via contact holes H5. In the exampleillustrated in FIG. 10, two contact holes H5 are provided, but thenumber of the contact holes H5 may be one or three or more.

The conductive layer 51 is provided to overlap with the second wireASL2, and is electrically coupled to the second wire ASL2 via contactholes H6.

In this manner, the first wire ASL1, the second wire ASL2, the thirdwire ASL3, and the conductive layer 51 are electrically coupled to oneanother. Thus, when a potential is applied to any one of the first wireASL1, the second wire ASL2, the third wire ASL3, and the conductivelayer 51, all the remaining ones can be set to have the same potential.The increase in parasitic capacitances between the first wire ASL1, thesecond wire ASL2, the third wire ASL3, and the conductive layer 51 issuppressed.

The first wire ASL1 is provided between the gate line GCL and thedetection electrode 25 along one side of the detection electrode 25. Thefirst wire ASL1 is provided in the same layer as the gate line GCL.Thus, the parasitic capacitance between the detection electrode 25 andthe gate line GCL can be reduced. The third wire ASL3 is provided tooverlap with the gate line GCL. The conductive layer 51 is provided tooverlap with the detection electrode 25 except for a part where thedetection electrode 25 and the drain electrode 63 are coupled to eachother. This arrangement enables the parasitic capacitance between thedetection electrode 25 and the gate line GCL to be further reduced. Thethird wire ASL3 has a width larger than the width of the gate line GCL.Without being limited thereto, the third wire ASL3 may have the samewidth as that of the gate line GCL or a width smaller than that of thegate line GCL.

The semiconductor layer 61 is provided with a channel portion in aregion overlapping with the gate electrode 64. It is preferred that thethird wire ASL3 be provided at the position overlapping with the channelportion and have an area larger than that of the channel portion. Theabove-mentioned metal material is used for the third wire ASL3, and thethird wire ASL3 has a light transmittance smaller than that of thesubstrate 21. In the first embodiment, the third wire ASL3 is provided,and hence light entering the semiconductor layer 61 from the firstsurface 21 a side is blocked.

The planarization layer 59 illustrated in FIG. 11 is, for example, anorganic planarization film. For the protective layer 77 provided on theplanarization layer 59, for example, a translucent conductive materialsuch as indium tin oxide (ITO) or an inorganic material such as siliconoxide (SiO₂) is used. In this manner, the entry of moisture into theplanarization layer 59 can be suppressed to suppress the occurrence ofcorrosion of the detection electrode 25, the first wire ASL1, the secondwire ASL2, the third wire ASL3, and the conductive layer 51. Theprotective layer 77, which uses the conductive material such as ITO,functions as a shield configured to block electromagnetic noise such asstatic electricity that enters from the outside.

Next, a drive method for the fingerprint detection device according tothe first embodiment is described. FIG. 12 is a timing waveform diagramof the fingerprint detection device according to the first embodiment.

As illustrated in FIG. 12, in a detection period Pt1, the n-th gate lineGCL(n) (refer to FIG. 9) is selected, and a scanning signal Vscan(n) isturned on (High level). Switching elements Tr corresponding to adetection electrode block 25A(n) in the n-th row are turned on (open).Accordingly, a drive signal Vf is supplied to the respective detectionelectrodes 25 in the detection electrode block 25A(n) through data linesSGL(m), SGL(m+1), and SGL(m+2). A detection signal Vdet is output to thedetection unit 40 (refer to FIG. 1) from each detection electrode 25 inthe detection electrode block 25A(n) on the basis of the fundamentalprinciple of self-capacitance fingerprint detection described above.

In the detection period Pt1, scanning signals Vscan for gate linesGCL(n+1) and GCL(n+2) other than the gate line GCL(n) are off (Lowlevel), and each detection electrode 25 in a detection electrode block25A(n+1) and a detection electrode block 25A(n+2) is in the floatingstate in which a fixed potential is not supplied. Thus, parasiticcapacitances between the detection electrode 25 in the detectionelectrode block 25A(n) selected as a detection target and the detectionelectrode 25 in the unselected detection electrode block 25A(n+1) andbetween the detection electrode 25 in the detection electrode block25A(n) and the detection electrode 25 in the unselected detectionelectrode block 25A(n+2) can be suppressed. In the detection period Pt1,the first wire ASL1, the second wire ASL2, the third wire ASL3, and theconductive layer 51 are supplied with a signal Vsg1. Thus, the parasiticcapacitance between each detection electrode 25 in the detectionelectrode block 25A(n) selected as a detection target and the gate lineGCL is suppressed to suppress the deterioration in detectionsensitivity.

Next, in a detection period Pt2, the gate line GCL(n+1) in the (n+1)throw is selected, and a scanning signal Vscan(n+1) is turned on (Highlevel). Switching elements Tr in the detection electrode block 25A(n+1)in the (n+1)th row are turned on (open). Accordingly, the drive signalVf is supplied to the respective detection electrodes 25 in thedetection electrode block 25A(n+1) through the data lines SGL(m),SGL(m+1), and SGL(m+2), and the detection signal Vdet is output to thedetection unit 40 (refer to FIG. 1) from each detection electrode 25 inthe detection electrode block 25A(n+1).

In the detection period Pt2, each detection electrode 25 in thedetection electrode block 25A(n) and the detection electrode block25A(n+2) is in the floating state in which a fixed potential is notsupplied. The first wire ASL1, the second wire ASL2, the third wireASL3, and the conductive layer 51 are supplied with the signal Vsg1.

In a detection period Pt3, the gate line GCL(n+2) in the (n+2)th row isselected, and a scanning signal Vscan(n+2) is turned on (High level).Switching elements Tr in the detection electrode block 25A(n+2) in the(n+2)th row are turned on (open). Accordingly, the drive signal Vf issupplied to the respective detection electrodes 25 in the detectionelectrode block 25A(n+2) through the data lines SGL(m), SGL(m+1), andSGL(m+2), and the detection signal Vdet is output to the detection unit40 (refer to FIG. 1) from each detection electrode 25 in the detectionelectrode block 25A(n+2). This operation is sequentially repeated tocarry out the detection operation in the entire detection region 21 c.

As described above, the fingerprint detection device 1 according to thefirst embodiment includes: the substrate 21 having the first surface 21a and the second surface 21 b on the opposite side of the first surface21 a; the first surface 21 a serving as a detection surface fordetecting unevenness of an object in contact or in proximity; thedetection electrode 25 provided on the second surface 21 b side of thesubstrate 21, for detecting unevenness of a finger in contact or inproximity on the basis of an electrostatic capacitance change; and thedrive circuit provided on the second surface 21 b side of the substrate21, for supplying a drive signal to the detection electrode 25.

The detection electrode 25, the switching element Tr, the control IC 19,and the flexible substrate 36 are provided on the second surface 21 b onthe opposite side of the detection surface. Thus, the fixation of thesubstrate 21 to the casing 101 of the electronic apparatus is lessrestricted by the bump of the control IC 19, the flexible substrate 36,and other components. Specifically, the structure of the casing 101 towhich the first surface 21 a side of the substrate 21 is to be fixed canbe simplified to facilitate processing. No conductor such as the gateline GCL and the data line SGL is present on the first surface 21 a sidewith respect to the detection electrode 25, and hence detection errorsand the reduction in detection sensitivity can be suppressed.

Second Embodiment

FIG. 13 is an enlarged plan view of a detection electrode according to asecond embodiment. FIG. 14 is a sectional view taken along the lineXIV-XIV′ in FIG. 13.

In the second embodiment, the first wire ASL1, the second wire ASL2, andthe third wire ASL3 are not provided, but a fourth wire ASL4 thatsurrounds the detection electrode 25 is provided. As illustrated in FIG.13, the fourth wire ASL4 includes a first part ASL4 a, a second partASL4 b, a third part ASL4 c, and a fourth part ASL4 d. The gate line GCLis provided along a side 25 a of the detection electrode 25, and thefirst part ASL4 a is provided between the side 25 a of the detectionelectrode 25 and the gate line GCL along the side 25 a of the detectionelectrode 25 and the gate line GCL. The second part ASL4 b is providedon the opposite side of the first part ASL4 a across the detectionelectrode 25, and is provided along a side 25 b of the detectionelectrode 25. The third part ASL4 c is provided between the detectionelectrode 25 and the data line SGL, and is provided along a side 25 c ofthe detection electrode 25. The fourth part ASL4 d is provided on theopposite side of the third part ASL4 c across the detection electrode25, and is provided along a side 25 d of the detection electrode 25.Although not illustrated in FIG. 13, another gate line GCL is providedon the opposite side of the gate line GCL across the detection electrode25 (refer to FIG. 9), and the second part ASL4 b is provided between thegate line GCL and the detection electrode 25.

The first part ASL4 a and the second part ASL4 b, which are providedacross the detection electrode 25, are coupled to each other by thethird part ASL4 c and the fourth part ASL4 d. In this manner, the fourthwire ASL4 has a frame shape that surrounds the detection electrode 25.As illustrated in FIG. 13 and FIG. 14, the fourth wire ASL4 iselectrically coupled to the conductive layer 51 via contact holes H7.FIG. 13 illustrates only one detection electrode 25, but the conductivelayer 51 and the fourth wire ASL4 are provided for each of the detectionelectrodes 25 arranged in a matrix pattern. As illustrated in FIG. 13,the second part ASL4 b extends to the outer side of connection portionswith the third part ASL4 c and the fourth part ASL4 d in the rowdirection, and is continuous correspondingly to the detection electrodes25 arranged in the row direction. The fourth wires ASL4 arranged in therow direction are electrically coupled to one another by the second partASL4 b. The above-mentioned signal Vsg1 is supplied through the secondpart ASL4 b to the fourth wires ASL4 and conductive layers 51 arrangedin the row direction. The structure for coupling the fourth wires ASL4together is not limited thereto. For example, the first part ASL4 a maybe extended, or a wire that connects the fourth wires ASL4 together maybe coupled to the third part ASL4 c and the fourth part ASL4 d.

As illustrated in FIG. 14, the detection electrode 25 is provided in thesame layer as the gate line GCL. The fourth wire ASL4 is provided in thesame layer as the detection electrode 25 and the gate line GCL.Specifically, the insulating layer 58 a is provided on the secondsurface 21 b of the substrate 21, and the semiconductor layer 61 isprovided on the insulating layer 58 a. The insulating layer 58 b isprovided on the semiconductor layer 61, and the gate line GCL, thedetection electrode 25, and the fourth wire ASL4 are provided on theinsulating layer 58 b. The insulating layer 58 c is provided on the gateline GCL, the detection electrode 25, and the fourth wire ASL4, and thedata line SGL, the drain electrode 63, and the conductive layer 51 areprovided on the insulating layer 58 c.

The fourth wire ASL4 is provided to surround the periphery of thedetection electrode 25. The fourth wire ASL4 and the conductive layer 51are electrically coupled to each other. Thus, the detection electrode 25is surrounded by the fourth wire ASL4 and the conductive layer 51 exceptfor a surface opposed to the detection surface. When the signal Vsg1 issupplied to the fourth wire ASL4, the signal Vsg1 is supplied to thefourth wire ASL4 and the conductive layer 51. Consequently, theparasitic capacitance between the detection electrode 25 and the gateline GCL can be further reduced.

The fourth wire ASL4 and the detection electrode 25 are provided in thesame layer, and hence the wire forming step corresponding to one layercan be omitted as compared with the first embodiment. In this manner,the manufacturing process can be simplified to reduce the manufacturingcost.

FIG. 15 is an enlarged plan view of a detection electrode according to amodification of the second embodiment. As illustrated in FIG. 15, in thepresent modification, the first part ASL4 a and the second part ASL4 bof the fourth wire ASL4 are provided, but the third part ASL4 c and thefourth part ASL4 d are not provided. The first part ASL4 a is providedbetween the detection electrode 25 and the gate line GCL along the side25 a of the detection electrode 25. The second part ASL4 b is providedbetween the detection electrode 25 and another gate line GCL (notillustrated) along the side 25 b of the detection electrode 25 on theopposite side of the side 25 a. The second part ASL4 b is continuouscorrespondingly to the detection electrodes 25 arranged in the rowdirection. The first part ASL4 a is electrically coupled to theconductive layer 51 via the contact holes H7. The second part ASL4 b iselectrically coupled to the conductive layer 51 via contact holes H8.Accordingly, the signal Vsg1 is supplied through the second part ASL4 bto the conductive layers 51 and first parts ASL4 a arranged in the rowdirection.

By providing the fourth wire ASL4 at least between the detectionelectrode 25 and the gate line GCL in this manner, the parasiticcapacitance between the detection electrode 25 and the gate line GCL canbe reduced.

The fourth wire ASL4 may be configured such that the first part ASL4 a,the second part ASL4 b, and the third part ASL4 c illustrated in FIG. 13are provided and the fourth part ASL4 d is omitted.

Third Embodiment

FIG. 16 is an enlarged plan view of a detection electrode according to athird embodiment. FIG. 17 is a sectional view taken along the lineXVII-XVII′ in FIG. 16.

In the third embodiment, similarly to the first embodiment, the firstwire ASL1, the second wire ASL2, the third wire ASL3, and the conductivelayer 51 are provided. As illustrated in FIG. 17, the third embodimentis different from the first embodiment in employing what is called abottom gate structure in which the gate electrode 64 (gate line GCL) isprovided closer to the substrate 21 than the semiconductor layer 61 is.

As illustrated in FIG. 17, the third wire ASL3 and the detectionelectrode 25 are provided on the second surface 21 b of the substrate21. The insulating layer 58 a is provided on the third wire ASL3 and thedetection electrode 25. The gate line GCL and the first wire ASL1 areprovided on the insulating layer 58 a. The insulating layer 58 b isprovided on the gate line GCL and the first wire ASL1, and thesemiconductor layer 61 is provided on the insulating layer 58 b. Theinsulating layer 58 c is provided on the semiconductor layer 61, and thedrain electrode 63, the data line SGL, and the conductive layer 51 areprovided on the insulating layer 58 c. The planarization layer 59 isprovided on the drain electrode 63, the data line SGL, and theconductive layer 51, and the protective layer 77 is provided on theplanarization layer 59. The second wire ASL2 (not illustrated in FIG.17) is provided in the same layer as the gate line GCL and the firstwire ASL1.

In the third embodiment, the detection electrode 25 is provided closerto the second surface 21 b of the substrate 21 than the gate line GCLis. The insulating layer 58 a is provided between the detectionelectrode 25 and the gate line GCL. In other words, the detectionelectrode 25 is closer to the first surface 21 a serving as thedetection surface than the switching element Tr is. Only the substrate21 or the substrate 21 and the protective layer 29 are provided betweenthe detection electrode 25 and the detection surface. Thus, no conductorsuch as a wire is present on the first surface 21 a side with respect tothe detection electrode 25, and the distance between a finger in contactwith the detection surface and the detection electrode 25 is reduced.Consequently, the deterioration in detection sensitivity can besuppressed.

The gate line GCL is disposed closer to the substrate 21 than thesemiconductor layer 61 is, and hence the distance between the third wireASL3 and the gate line GCL is reduced. Thus, the parasitic capacitancebetween the gate line GCL and the detection electrode 25 is reduced.

Fourth Embodiment

FIG. 18 is an enlarged plan view of a detection electrode according to afourth embodiment. FIG. 19 is a sectional view taken along the lineXIX-XIX′ in FIG. 18. In the fourth embodiment, similarly to the secondembodiment, the first wire ASL1, the second wire ASL2, and the thirdwire ASL3 are not provided, but the fourth wire ASL4 that surrounds thedetection electrode 25 is provided. As illustrated in FIG. 19, thefourth embodiment employs what is called a bottom gate structure inwhich the gate electrode 64 (gate line GCL) is provided closer to thesubstrate 21 than the semiconductor layer 61 is.

As illustrated in FIG. 19, the gate line GCL, the fourth wire ASL4, andthe detection electrode 25 are provided on the second surface 21 b ofthe substrate 21. The insulating layer 58 a is provided on the gate lineGCL, the fourth wire ASL4, and the detection electrode 25. Thesemiconductor layer 61 is provided on the insulating layer 58 a. Theinsulating layer 58 b is provided on the semiconductor layer 61, and thedrain electrode 63, the data line SGL, and the conductive layer 51 areprovided on the insulating layer 58 b. The planarization layer 59 isprovided on the drain electrode 63, the data line SGL, and theconductive layer 51, and the protective layer 77 is provided on theplanarization layer 59.

In the fourth embodiment, the detection electrode 25 is provided on thesecond surface 21 b of the substrate 21 in the same layer as the gateline GCL. Thus, the detection electrode 25 is disposed at the positionclose to the first surface 21 a serving as the detection surface, andhence the distance between a finger in contact or in proximity and thedetection electrode 25 can be reduced to suppress the deterioration indetection sensitivity.

As illustrated in FIG. 18, the second part ASL4 b extends to the outerside of connection portions with the third part ASL4 c and the fourthpart ASL4 d in the row direction, and is continuous correspondingly tothe detection electrodes 25 arranged in the row direction. The fourthwires ASL4 arranged in the row direction are electrically coupled to oneanother by the second part ASL4 b. The above-mentioned signal Vsg1 issupplied through the second part ASL4 b to the fourth wires ASL4 andconductive layers 51 arranged in the row direction. The fourth wire ASL4is provided to surround the detection electrode 25, and hence theparasitic capacitance between the detection electrode 25 and the gateline GCL can be reduced. The gate line GCL, the fourth wire ASL4, andthe detection electrode 25 are provided in the same layer, and hence thenumber of laminated layers can be reduced to simplify the manufacturingprocess.

In the fourth embodiment, for example, the fourth wire ASL4 may beconfigured such that the first part ASL4 a and the second part ASL4 billustrated in FIG. 18 are provided but the third part ASL4 c and thefourth part ASL4 d are omitted. The fourth wire ASL4 may be configuredsuch that the first part ASL4 a, the second part ASL4 b, and the thirdpart ASL4 c are provided but the fourth part ASL4 d is omitted. Asillustrated in FIG. 19, the insulating layer 58 a and the insulatinglayer 58 b are provided between the substrate 21 and the planarizationlayer 59. The fourth embodiment can reduce the number of insulatinglayers by one as compared with what is called the top gate structureillustrated in FIG. 14, thereby thinning the fingerprint detection unit30.

Fifth Embodiment

FIG. 20 is a block diagram illustrating a configuration example of adisplay device according to a fifth embodiment. As illustrated in FIG.20, a display device 2 includes a display unit 10 with a fingerprintdetection function, a control unit 11, a display gate driver 12A, adetection gate driver 12B, a source driver 13, a detection electrodedriver 14, and a detection unit 40. The display device 2 is a displaydevice in which the display unit 10 with the fingerprint detectionfunction has the fingerprint detection function incorporated therein.The display unit 10 with the fingerprint detection function is a deviceobtained by integrating a display panel 20 that uses a liquid crystaldisplay element as a display element and a fingerprint detection unit 30configured to detect the unevenness of a finger in contact or inproximity. The display panel 20 may be a device obtained by integratinga touch panel configured to detect a touch input position or a deviceobtained by mounting a touch panel on the display panel 20.

The display panel 20 is an element configured to perform display bysequentially scanning horizontal lines one by one in accordance with ascanning signal Vscan supplied from the display gate driver 12A.

The display gate driver 12A has a function of sequentially selecting onehorizontal line as a display drive target by the display unit 10 withthe fingerprint detection function on the basis of a control signalsupplied from the control unit 11.

The source driver 13 is a circuit configured to supply a pixel signalVpix to each subpixel SPix in the display unit 10 with the fingerprintdetection function on the basis of a control signal supplied from thecontrol unit 11.

The fingerprint detection unit 30 performs detection by sequentiallyscanning detection lines one by one in accordance with a scanning signalVscan supplied from the detection gate driver 12B. The fingerprintdetection unit 30 detects the shape of a fingerprint by detecting theunevenness of a finger in contact or in proximity on the basis of theprinciple of self-capacitance detection.

The detection electrode driver 14 is a circuit configured to supply adrive signal Vf to a detection electrode 25 subjected to detectiondriving by the fingerprint detection unit 30 on the basis of a controlsignal supplied from the control unit 11.

The control unit 11 is a circuit configured to supply the controlsignals to the display gate driver 12A and the source driver 13 tocontrol display operation on the basis of an image signal supplied fromthe outside. The control unit 11 is a circuit configured to supply thecontrol signals to the detection gate driver 12B, the detectionelectrode driver 14, and the detection unit 40 to control the detectiongate driver 12B, the detection electrode driver 14, and the detectionunit 40 so as to perform fingerprint detection operation insynchronization with one another. The control unit 11 may independentlycontrol the display operation and the fingerprint detection operation,or may control the display operation and the fingerprint detectionoperation in synchronization with each other.

Next, a configuration example of the display device 2 is described indetail. FIG. 21 is a sectional view illustrating a schematic sectionalstructure of the display device according to the fifth embodiment. Asillustrated in FIG. 21, the display device 2 includes a first substrate21A, a second substrate 22, detection electrodes 25, reflectionelectrodes 28, a liquid crystal layer 6, and a front light unit 4.

The first substrate 21A has a first surface 21Aa and a second surface21Ab on the opposite side of the first surface 21Aa. The detectionelectrodes 25 are provided on the first surface 21Aa side of the firstsubstrate 21A. The detection electrodes 25 can detect a fingerprint of afinger in contact with the second surface 21Ab of the first substrate21A on the basis of the fundamental principle of self-capacitancefingerprint detection described above. The second surface 21Ab of thefirst substrate 21A functions as a detection surface used for thefingerprint detection unit 30 to detect a fingerprint.

A glass substrate can be used as the first substrate 21A. For example,the use of toughened glass enables the first substrate 21A to be thinnedwhile the strength is maintained. This configuration enables thedistance between the second surface 21Ab, which is the detection surfacefor fingerprint detection, and the detection electrode 25 to be reducedto improve the detection sensitivity. Examples of toughened glass thatcan be used include, but are not limited to, chemically toughened glassin which a compressive stress layer is formed on the surface byexchanging sodium (Na) ions on the surface of glass with potassium (K)ions having larger ion radius, toughened glass in which a compressivestress layer is formed on the surface by supplying air to a heated glasssubstrate for quenching, for example. The first substrate 21A may besix-sided toughened glass.

The reflection electrodes 28 are provided on the first surface 21Aa sideof the first substrate 21A so as to be opposed to the detectionelectrodes 25. The second substrate 22 has a first surface 22 a and asecond surface 22 b on the opposite side of the first surface 22 a. Thesecond surface 22 b of the second substrate 22 is disposed to be opposedto the first surface 21Aa of the first substrate 21A. A color filter 32and a translucent electrode 23 that uses a translucent conductivematerial such as indium tin oxide (ITO) are provided on the secondsurface 22 b side of the second substrate 22. The translucent electrode23 is electrically coupled to the first substrate 21A side through aconnection portion (not illustrated) and supplied with a commonpotential Vcom. An optical function layer 145, which includes apolarization plate, a ¼ wavelength plate or the like, and the frontlight unit 4 are provided on the first surface 22 a side of the secondsubstrate 22.

The reflection electrode 28 is disposed to correspond to one subpixelSPix. External light entering the second substrate 22 side is reflectedby the reflection electrode 28, and the reflected light is modulated bythe liquid crystal layer 6 to implement the display. The first surface22 a of the second substrate 22 functions as a display surface of thedisplay panel 20. A metal material such as aluminum (Al) is used for thereflection electrode 28. A configuration in which an ITO layer islaminated on the reflection electrode 28 to inhibit corrosion can beemployed. Another configuration in which bump is formed on thereflection electrode 28 to improve diffusivity of the reflected lightcan be employed. The reflection electrode 28 may be mirror-finished toimprove reflectivity so as to improve the luminance. Circuit elements,including a switching element such as a thin film transistor (TFT) and acapacitive element, are formed between the detection electrode 25 andthe reflection electrode 28 for each subpixel SPix.

The liquid crystal layer 6 is provided between the translucent electrode23 and the reflection electrode 28. The liquid crystal layer 6 modulateslight passing therethrough in accordance with the state of electricfield. The liquid crystal layer 6 is formed by sealing a liquid crystalmaterial between the translucent electrode 23 and the reflectionelectrode 28.

The display panel 20 according to the fifth embodiment is a displaydevice using a liquid crystal display (LCD) panel. In particular, areflective liquid crystal display device is used. The reflective liquidcrystal display device may be either a monochrome display-compatibledisplay device or a color display-compatible display device. When thedisplay device is compatible with color display, one display pixel as aunit for forming a color image includes a plurality of subpixels. Morespecifically, in the color display-compatible display device, forexample, one display pixel includes three subpixels: a subpixel fordisplaying red (R), a subpixel for displaying green (G), and a subpixelfor displaying blue (B). One pixel may include four or more subpixels,and the colors may be other than red, green, and blue.

In the color filter 32, for example, color regions of color filterscolored with red (R), green (G), and blue (B) may be periodicallyarranged. Color regions of three colors of R, G, and B as a set areassociated with each subpixel SPix, and the subpixels SPix correspondingto the three color regions as a set form the pixel Pix. The color filter32 is opposed to the liquid crystal layer 6 in a direction perpendicularto the first substrate 21A. The color filter 32 may have a combinationof different colors as long as the color regions are colored withdifferent colors. The color filter 32 is not limited to a combination ofthree colors, and may have a combination of four or more colors.

The front light unit 4 is disposed on the first surface 22 a side of thesecond substrate 22. The first surface 22 a is a surface on the sidewhere an image of the display panel 20 is displayed, that is, a surfacethat external light enters and a surface from which light reflected bythe reflection electrode 28 exits. The front light unit 4 includes alight source 140, a light guide plate 144, and an adhesive member 146. Alight emitting diode (LED) 142 is used for the light source 140. Anotherlight source such as a fluorescent tube may be used for the light source140. The light guide plate 144 is a transparent plate-shaped member, andis laminated above the first surface 22 a of the second substrate 22with the optical function layer 145 and the adhesive member 146interposed therebetween. In the light guide plate 144, a large number ofgrooves may be formed in a surface 144 a opposed to the second substrate22. The light guide plate 144 can reflect and scatter incident lightfrom the light source 140 so that the light is output toward the secondsubstrate 22.

The light output toward the second substrate 22 passes through thetranslucent electrode 23 and the liquid crystal layer 6 and is reflectedby the reflection electrode 28, and then passes through the light guideplate 144 to reach the eyes of an observer. A region where the lightoutput toward the second substrate 22 is blocked and a region where thelight transmits are switched depending on the state of liquid crystal atthe light passing position as described above, thereby displaying animage on the display surface.

FIG. 22 is a circuit diagram illustrating a fundamental pixel circuit.FIG. 22 illustrates a pixel circuit for the display panel 20, and theillustration of circuits such as the wire for the fingerprint detectionunit 30 is omitted. As illustrated in FIG. 22, a plurality of displaydata lines SGLd and a plurality of display gate lines GCLd are wired soas to intersect with each other. The direction in which the display datalines SGLd extend is the column direction, and the direction in whichthe display gate lines GCLd extend is the row direction.

The subpixels SPix are arranged in a matrix pattern, and each include adisplay switching element Trd, a liquid crystal capacitance 76A, and aholding capacitance 76B. The display switching element Trd has a sourcecoupled to the display data line SGLd, a gate coupled to the displaygate line GCLd, and a drain coupled to one end of the liquid crystalcapacitance 76A and one end of the holding capacitance 76B.

The liquid crystal capacitance 76A represents a capacitive componentgenerated between the reflection electrode 28 and the translucentelectrode 23. The holding capacitance 76B is a capacitive component forholding an image display voltage applied between the reflectionelectrode 28 and the translucent electrode 23.

The subpixel SPix is coupled to other subpixels SPix belonging to thesame row in the display panel 20 by the display gate line GCLd. Thedisplay gate line GCLd is coupled to the display gate driver 12A andsupplied with the scanning signal Vscan from the display gate driver12A. The subpixel SPix is coupled to other subpixels SPix belonging tothe same column in the display panel 20 by the display data line SGLd.The display data line SGLd is coupled to the source driver 13 andsupplied with the pixel signal Vpix from the source driver 13.

The display gate driver 12A is driven to sequentially scan the displaygate lines GCLd. The display gate driver 12A applies the scanning signalVscan (refer to FIG. 1) to the gates of the display switching elementsTrd in the subpixels SPix through the display gate line GCLd, therebysequentially selecting one line (one horizontal line) of the subpixelsSPix as a display drive target. The source driver 13 supplies the pixelsignal Vpix to the subpixels SPix forming the selected one horizontalline through the display data line SGLd. In these subpixels SPix,display is performed for each horizontal line in accordance with thesupplied pixel signal Vpix.

Next, the configurations of the detection electrode 25 and thereflection electrode 28 are described with reference to FIG. 23 to FIG.26. FIG. 23 is a plan view illustrating a planar structure of thedisplay device according to the fifth embodiment. FIG. 24 is an enlargedplan view of a portion corresponding to one subpixel. FIG. 25 is asectional view taken along the line XXV-XXV′ in FIG. 24. FIG. 26 is asectional view taken along the line XXVI-XXVI′ in FIG. 24. FIG. 23 andFIG. 24 illustrate plan views when the first surface 21Aa of the firstsubstrate 21A is viewed from the second surface 22 side. FIG. 24 omitsthe illustration of the reflection electrode 28 for simplicity.

As illustrated in FIG. 23, the display gate line GCLd is provided alongthe row direction, and the display gate lines GCLd are arranged withintervals in the column direction. The display data line SGLd isprovided along the column direction, and the display data lines SGLd arearranged with intervals in the row direction. A detection gate line GCLsis provided in parallel to the display gate line GCLd, and the detectiongate lines GCLs are arranged along the row direction with intervals inthe column direction. A detection data line SGLs is provided in parallelto the display data line SGLd, and the detection data lines SGLs arearranged along the column direction with intervals in the row direction.The reflection electrode 28 is disposed in a region surrounded by thedisplay gate line GCLd, the display data line SGLd, the detection gateline GCLs, and the detection data line SGLs. The region surrounded bythe display gate line GCLd, the display data line SGLd, the detectiongate line GCLs, and the detection data line SGLs corresponds to onesubpixel SPix. The reflection electrode 28 has a substantiallyrectangular shape, and the reflection electrodes 28 are arranged in amatrix pattern. The detection electrode 25 and a holding capacitanceelectrode 75 are provided to overlap with the corresponding reflectionelectrode 28. In other words, the detection electrodes 25 are arrangedin a matrix pattern to correspond to the reflection electrodes 28.

As illustrated in FIG. 24, the display switching element Trd is providednear the position at which the display gate line GCLd and the displaydata line SGLd intersect with each other. The display switching elementTrd is provided at the position corresponding to the reflectionelectrode 28 in one subpixel SPix. A drain electrode 73 of the displayswitching element Trd is provided to overlap with the holdingcapacitance electrode 75, and a holding capacitance is formed betweenthe drain electrode 73 and the holding capacitance electrode 75. Theholding capacitance electrode 75 is coupled to adjacent holdingcapacitance electrodes arranged in the row direction through connectionparts 75 a.

A detection switching element Trs is provided near the position at whichthe detection gate line GCLs and the detection data line SGLs intersectwith each other. The detection switching element Trs is provided at theposition corresponding to the detection electrode 25.

The display switching element Trd and the detection switching elementTrs are formed of thin film transistors. In the present example, thedisplay switching element Trd and the detection switching element Trsare formed of re-channel metal oxide semiconductor (MOS) TFT elements.

The detection gate driver 12B (refer to FIG. 1) sequentially selects thedetection gate lines GCLs. The detection gate driver 12B supplies thescanning signal Vscan to the detection switching elements Trs throughthe selected detection gate line GCLs. In this manner, the detectiongate driver 12B selects one line (one horizontal line) of the detectionelectrodes 25 as a detection electrode block 25A to be detected. Thedetection electrode block 25A includes a plurality of detectionelectrodes 25 arranged in the row direction. The detection electrodedriver 14 (refer to FIG. 1) supplies the drive signal Vf to eachdetection electrode 25 in the detection electrode block 25A through thedetection data line SGLs. The detection unit 40 receives a detectionsignal Vdet corresponding to an electrostatic capacitance change in eachdetection electrode 25 in accordance with the fundamental principle ofself-capacitance fingerprint detection described above. In this manner,a fingerprint of a finger in touch with the detection surface isdetected.

Conductive fifth wire ASL5 is provided to overlap with the detectiongate line GCLs along the detection gate line GCLs. A sixth wire ASL6 isprovided to overlap with the display gate line GCLd along the displaygate line GCLd. The fifth wire ASL5 and the sixth wire ASL6 are providedto be continuous correspondingly to the subpixels SPix arranged in therow direction.

As illustrated in FIG. 24, a seventh wire ASL7 that surrounds theperiphery of the detection electrode 25 is provided. The seventh wireASL7 has a part that extends along the detection gate line GCLs betweenthe detection electrode 25 and the detection gate line GCLs and a partthat extends along the display gate line GCLd between the detectionelectrode 25 and the display gate line GCLd. A conductive layer ASL8 isfurther provided so as to cover the detection electrode 25 and theseventh wire ASL7.

For example, a metal material of at least one of molybdenum (Mo),aluminum (Al), copper (Cu), silver (Ag), or an alloy thereof can be usedfor the fifth wire ASL5, the sixth wire ASL6, the seventh wire ASL7, andthe conductive layer ASL8.

As described above, the display gate line GCLd and the detection gateline GCLs are supplied with the signal (scanning signal Vscan) differentfrom the drive signal Vf supplied to the detection data line SGLs andthe detection electrode 25. Thus, a parasitic capacitance between thedisplay gate line GCLd and the detection electrode 25 and a parasiticcapacitance between the display data line SGLd and the detectionelectrode 25 can increase. A parasitic capacitance between the detectiongate line GCLs and the detection electrode 25 and a parasiticcapacitance between the detection gate line GCLs and the detection dataline SGLs can increase. When the parasitic capacitance increases, theelectrostatic capacitance change caused by contact or proximity of afinger is relatively reduced, and detection sensitivity can deteriorate.

In the fifth embodiment, the detection electrode driver 14 supplies thefifth wire ASL5, the sixth wire ASL6, the seventh wire ASL7, and theconductive layer ASL8 with the signal Vsg1 that is synchronized with thedrive signal Vf and has the same waveform as the drive signal Vf. Thus,the parasitic capacitance is reduced. Consequently, detection errors andthe deterioration in detection sensitivity are suppressed. A drivecircuit that is not provided in the detection electrode driver 14 may beprovided as appropriate to supply the signal Vsg1. By providing thefifth wire ASL5, the sixth wire ASL6, the seventh wire ASL7, and theconductive layer ASL8, a fluctuation in the liquid crystal capacitance76A caused by the fingerprint detection operation can be suppressed tosuppress the deterioration in display image.

Next, the configurations of the detection electrode 25, each wire, andthe conductive layer are described in detail. As illustrated in FIG. 25,the detection switching element Trs includes a semiconductor layer 61, asource electrode 62, a drain electrode 63, and a gate electrode 64. Asthe material for the semiconductor layer 61, a well-known material suchas polysilicon and oxide semiconductor can be used.

The semiconductor layer 61 is electrically coupled to the detection dataline SGLs via a contact hole H1. A part of the detection data line SGLsthat overlaps with the semiconductor layer 61 functions as the sourceelectrode 62. The semiconductor layer 61 is bent so as to intersect withthe detection gate line GCLs a plurality of times in a plan view. A partof the detection gate line GCLs that overlaps with the semiconductorlayer 61 functions as the gate electrode 64. The semiconductor layer 61is electrically coupled to the drain electrode 63 via a contact hole H2.The drain electrode 63 intersects with the seventh wire ASL7 to overlapwith the detection electrode 25. The drain electrode 63 is electricallycoupled to the detection electrode 25 via a contact hole H3.

As illustrated in FIG. 25, the fifth wire ASL5 and the detectionelectrode 25 are provided on the first surface 21Aa of the substrate 21.The insulating layer 58 a is provided on the fifth wire ASL5 and thedetection electrode 25. The semiconductor layer 61 is provided on theinsulating layer 58 a. The insulating layer 58 b is provided on thesemiconductor layer 61, and the detection gate line GCLs and the seventhwire ASL7 are provided on the insulating layer 58 b. The insulatinglayer 58 c is provided on the detection gate line GCLs and the seventhwire ASL7, and the detection data line SGLs, the drain electrode 63, andthe conductive layer ASL8 are provided on the insulating layer 58 c. Theplanarization layer 59 is provided on the detection data line SGLs, thedrain electrode 63, and the conductive layer ASL8, and the reflectionelectrode 28 is provided on the planarization layer 59.

The translucent electrode 23, the color filter 32, and the secondsubstrate 22 are provided above the reflection electrode 28 with theliquid crystal layer 6 interposed therebetween.

As illustrated in FIG. 24, the fifth wire ASL5 is provided with a tabportion ASL5 a that protrudes to a position overlapping with theconductive layer ASL8. The tab portion ASL5 a is electrically coupled tothe conductive layer ASL8 via a contact hole H4. Accordingly, when theabove-mentioned signal Vsg1 is supplied to the fifth wire ASL5, thesignal Vsg1 is supplied to the conductive layer ASL8 through the tabportion ASL5 a. The seventh wire ASL7 is coupled to the conductive layerASL8 via a contact hole H5. Accordingly, the signal Vsg1 supplied to thefifth wire ASL5 is supplied to the seventh wire ASL7 through theconductive layer ASL8.

The semiconductor layer 61 is provided with a channel portion in aregion overlapping with the gate electrode 64. It is preferred that thefifth wire ASL5 be provided at a position overlapping with the channelportion and have an area larger than that of the channel portion. Theabove-mentioned metal material is used for the fifth wire ASL5, and thefifth wire ASL5 has a light transmittance smaller than that of the firstsubstrate 21A, and hence light that enters the semiconductor layer 61from the first substrate 21A side is blocked.

Next, the connection structure of the reflection electrode 28 and thedisplay switching element Trd is described. As illustrated in FIG. 26,the display switching element Trd includes a semiconductor layer 71, asource electrode 72, a drain electrode 73, and a gate electrode 74. Asthe material for the semiconductor layer 71, a well-known material suchas polysilicon and oxide semiconductor can be used. For example, the useof transparent amorphous oxide semiconductor (TAOS) or low temperaturepolysilicon (LTPS) enables the semiconductor layer 71 to have goodcapability of holding an image display voltage for a long period(holding rate), thereby improving the display quality. The same materialmay be used for the semiconductor layer 71 of the display switchingelement Trd and the semiconductor layer 61 of the detection switchingelement Trs.

As illustrated in FIG. 24 and FIG. 26, the semiconductor layer 71 iselectrically coupled to the display data line SGLd via a contact holeH6. A part of the display data line SGLd that overlaps with thesemiconductor layer 71 functions as the source electrode 72. Thesemiconductor layer 71 is bent so as to intersect with the display gateline GCLd a plurality of times in a plan view. A part of the displaygate line GCLd that overlaps with the semiconductor layer 71 functionsas the gate electrode 74. The semiconductor layer 71 is electricallycoupled to the drain electrode 73 via a contact hole H7. The drainelectrode 73 has an area larger than that of the drain electrode 63 ofthe detection switching element Trs, and overlaps with the holdingcapacitance electrode 75. The drain electrode 73 is electrically coupledto the reflection electrode 28 via a contact hole H8.

As illustrated in FIG. 26, the sixth wire ASL6 and the holdingcapacitance electrode 75 are provided on the first surface 21Aa of thesubstrate 21. The insulating layer 58 a is provided on the sixth wireASL6 and the holding capacitance electrode 75. The semiconductor layer71 is provided on the insulating layer 58 a. The insulating layer 58 bis provided on the semiconductor layer 71, and the display gate lineGCLd is provided on the insulating layer 58 b. The insulating layer 58 cis provided on the display gate line GCLd, and the display data lineSGLd and the drain electrode 73 are provided on the insulating layer 58c. The planarization layer 59 is provided on the display data line SGLdand the drain electrode 73, and the reflection electrode 28 is providedon the planarization layer 59.

The semiconductor layer 71 is provided with a channel portion in aregion overlapping with the gate electrode 74. It is preferred that thesixth wire ASL6 be provided at a position overlapping with the channelportion and have an area larger than that of the channel portion. Byproviding the sixth wire ASL6, for example, light that enters thesemiconductor layer 71 from the first substrate 21A side is blocked.

As illustrated in FIG. 25 and FIG. 26, the detection electrode 25, theholding capacitance electrode 75, the fifth wire ASL5, and the sixthwire ASL6 are provided in the same layer. The display switching elementTrd and the detection switching element Trs are provided in the samelayer. The detection electrode 25 and the holding capacitance electrode75 may be provided in different layers, and the display switchingelement Trd and the detection switching element Trs may be provided indifferent layers.

In the fifth embodiment, the detection electrode 25 is provided closerto the first surface 21Aa of the first substrate 21A than the detectiongate line GCLs is. The detection electrode 25 is provided closer to thefirst surface 21Aa of the first substrate 21A than the display gate lineGCLd is. The insulating layers 58 a and 58 b are provided between thedetection electrode 25 and the detection gate line GCLs and between thedetection electrode 25 and the display gate line GCLd. In other words,the detection electrode 25 is closer to the second surface 21Ab servingas the detection surface than the detection switching element Trs andthe display switching element Trd are. Only the first substrate 21A orthe first substrate 21A and a protective layer are provided between thedetection electrode 25 and the detection surface. Thus, no conductorsuch as a wire is present on the second surface 21Ab side with respectto the detection electrode 25, and the distance between a finger incontact with the detection surface and the detection electrode 25 isreduced. Consequently, the deterioration in detection sensitivity can besuppressed.

The reflection electrode 28 is provided on the first surface 21Aa sideof the first substrate 21A at a position farther away from the firstsurface 21Aa than the detection electrode 25 is. Thus, images can bedisplayed on the first surface 22 a of the second substrate 22.Consequently, in the display device 2 according to the fifth embodiment,the second surface 21Ab of the first substrate 21A functions as adetection surface for detecting a fingerprint of a finger in contact,and the first surface 22 a of the second substrate 22 on the oppositeside of the second surface 21Ab across the detection electrode 25functions as a display surface for displaying images. The reflectionelectrode 28 is formed to be non-transmissive in order to reflect lightfrom the display surface. Thus, circuits and electrodes can berelatively freely arranged between the reflection electrode 28 and thefirst substrate 21A on which the reflection electrode 28 is formed. Thefifth embodiment focuses on this point, and the detection electrode 25and other components are provided on the rear side of the reflectionelectrode 28 and the detection surface is provided on the surface on theopposite side of the display surface. Consequently, the display device 2according to the fifth embodiment enables fingerprints to be detected onthe surface on the opposite side of the display surface, and enablesfingerprints to be detected in the period during which the display isperformed.

Next, a drive method for the display device 2 according to the fifthembodiment is described. FIG. 27 is a timing waveform diagramillustrating an operation example of fingerprint detection operationaccording to the fifth embodiment. As illustrated in FIG. 27, detectionperiods Pt1, Pt2, and Pt3 during which the fingerprint detectionoperation is performed are arranged in a time division manner.

As illustrated in FIG. 27, in the detection period Pt1, the detectiongate line GCLs(n) (refer to FIG. 23) in the n-th row is selected, andthe scanning signal Vscan(n) is turned on (High level). When thescanning signal Vscan(n) is turned on (High level), detection switchingelements Trs corresponding to the detection electrode block 25A(n) inthe n-th row are turned on (open). Accordingly, the drive signal Vf issupplied to the respective detection electrodes 25 in the detectionelectrode block 25A(n) through the detection data lines SGLs(m),SGLs(m+1), and SGLs(m+2). The detection signal Vdet is output to thedetection unit 40 (refer to FIG. 1) from each detection electrode 25 inthe detection electrode block 25A(n) on the basis of the fundamentalprinciple of self-capacitance fingerprint detection described above.

In the detection period Pt1, the scanning signal Vscan for the detectiongate lines GCLs(n+1) and GCLs(n+2) other than the detection gate lineGCLs(n) is off (Low level), and each detection electrode 25 in thedetection electrode block 25A(n+1) and the detection electrode block25A(n+2) is in the floating state in which a fixed potential is notsupplied. Thus, parasitic capacitances between the detection electrode25 in the detection electrode block 25A(n) selected as a detectiontarget and the detection electrode 25 in the unselected detectionelectrode block 25A(n+1) and between the detection electrode 25 in thedetection electrode block 25A(n) and the detection electrode 25 in theunselected detection electrode block 25A(n+2) can be suppressed. In thedetection period Pt1, the fifth wire ASL5, the sixth wire ASL6, theseventh wire ASL7, and the conductive layer ASL8 are supplied with thesignal Vsg1. Thus, the parasitic capacitance between each detectionelectrode 25 in the detection electrode block 25A(n) selected as adetection target and the detection gate line GCLs is suppressed tosuppress the deterioration in detection sensitivity.

Next, in the detection period Pt2, the detection gate line GCLs(n+1) inthe (n+1)th row is selected, and the scanning signal Vscan(n+1) isturned on (High level). Detection switching elements Trs in thedetection electrode block 25A(n+1) in the (n+1)th row are turned on(open). Accordingly, the drive signal Vf is supplied to the respectivedetection electrodes 25 in the detection electrode block 25A(n+1)through the detection data lines SGLs(m), SGLs(m+1), and SGLs(m+2), andthe detection signal Vdet is output to the detection unit 40 (refer toFIG. 1) from each detection electrode 25 in the detection electrodeblock 25A(n+1).

In the detection period Pt2, each detection electrode 25 in thedetection electrode block 25A(n) and the detection electrode block25A(n+2) is in the floating state in which a fixed potential is notsupplied. The fifth wire ASL5, the sixth wire ASL6, the seventh wireASL7, and the conductive layer ASL8 are supplied with the signal Vsg1.

In the detection period Pt3, the detection gate line GCLs(n+2) in the(n+2)th row is selected, and the scanning signal Vscan(n+2) is turned on(High level). Detection switching elements Trs in the detectionelectrode block 25A(n+2) in the (n+2)th row are turned on (open).Accordingly, the drive signal Vf is supplied to the respective detectionelectrodes 25 in the detection electrode block 25A(n+2) through thedetection data lines SGLs(m), SGLs(m+1), and SGLs(m+2), and thedetection signal Vdet is output to the detection unit 40 (refer toFIG. 1) from each detection electrode 25 in the detection electrodeblock 25A(n+2). This operation is sequentially repeated to carry out thedetection operation on the entire detection surface.

In the fifth embodiment, the display gate driver 12A and the detectiongate driver 12B can be driven independently. In other words, in thedisplay device 2 according to the fifth embodiment, the display and thefingerprint detection can be driven independently. More specifically,the detection period Pt1 is provided in a period during which thedisplay gate line GCLd(n) is not selected, the detection period Pt2 isprovided in a period during which the display gate line GCLd(n+1) is notselected, and the detection period Pt3 is provided in a period duringwhich the display gate line GCLd(n+2) is not selected. Thus, thedeterioration in display image caused by the drive signal Vf suppliedfrom the detection electrode 25 in the fingerprint detection operationcan be suppressed.

In the fifth embodiment, the shapes of the reflection electrode 28, thedetection electrode 25, and the holding capacitance electrode 75 areillustrative, and can be changed to a rhombic, a parallelogram, or apolygon as appropriate. The fifth wire ASL5 and the sixth wire ASL6 havewidths larger than the widths of the detection gate line GCLs and thedisplay gate line GCLd, respectively. Without being limited thereto, thefifth wire ASL5 and the sixth wire ASL6 may have the same or smallerwidths than the detection gate line GCLs and the display gate line GCLd.The seventh wire ASL7 is provided continuously so as to surround theperiphery of the detection electrode 25, but without being limitedthereto, the seventh wire ASL7 only needs to be provided at leastbetween the detection electrode 25 and the detection gate line GCLs andbetween the detection electrode 25 and the display gate line GCLd.

Sixth Embodiment

FIG. 28 is an enlarged plan view of a portion corresponding to onesubpixel in a display device according to a sixth embodiment. FIG. 29 isa sectional view taken along the line XXIX-XXIX′ in FIG. 28. In thesixth embodiment, the holding capacitance electrode 75 for forming aholding capacitance is not provided.

As illustrated in FIG. 28 and FIG. 29, the connection structure of thedisplay switching element Trd and the reflection electrode 28 is thesame as in the fifth embodiment. The semiconductor layer 71 iselectrically coupled to the display data line SGLd via the contact holeH6. The semiconductor layer 71 is bent so as to intersect with thedisplay gate line GCLd a plurality of times in a plan view. Thesemiconductor layer 71 is electrically coupled to the drain electrode 73via the contact hole H7. The drain electrode 73 has an area larger thanthat of the drain electrode 63 of the detection switching element Trs.As illustrated in FIG. 28, the detection electrode 25 is provided toextend from the position near the detection gate line GCLs to theposition near the display gate line GCLd. The detection electrode 25includes a portion overlapping with the drain electrode 73. The drainelectrode 73 is electrically coupled to the reflection electrode 28 viathe contact hole H8. The seventh wire ASL7 is provided to surround theperiphery of the detection electrode 25, and includes a portion providedbetween the detection electrode 25 and the display gate line GCLd alongthe display gate line GCLd.

As illustrated in FIG. 29, the sixth wire ASL6 and the detectionelectrode 25 are provided on the first surface 21Aa of the substrate 21.The insulating layer 58 a is provided on the sixth wire ASL6 and thedetection electrode 25. The semiconductor layer 71 is provided on theinsulating layer 58 a. The insulating layer 58 b is provided on thesemiconductor layer 71, and the display gate line GCLd and the seventhwire ASL7 are provided on the insulating layer 58 b. The insulatinglayer 58 c is provided on the display gate line GCLd and the seventhwire ASL7, and the display data line SGLd and the drain electrode 73 areprovided on the insulating layer 58 c. The planarization layer 59 isprovided on the display data line SGLd and the drain electrode 73, andthe reflection electrode 28 is provided on the planarization layer 59.

In the sixth embodiment, the drain electrode 73 has a portion 73 aoverlapping with the detection electrode 25, and hence a holdingcapacitance is formed between the drain electrode 73 and the detectionelectrode 25. In this manner, the deterioration in display image can besuppressed. The detection electrode 25 can be provided in the region inwhich the holding capacitance electrode 75 is otherwise formed, andhence the area of the detection electrode 25 can be increased to improvethe detection sensitivity of fingerprint detection.

Seventh Embodiment

FIG. 30 is a sectional view illustrating a sectional structure of adisplay device according to a seventh embodiment. A display panel 20according to the seventh embodiment is a display panel using organiclight-emitting diodes (OLEDs).

As illustrated in FIG. 30, a display device 2A includes the detectionelectrode 25, the display switching element Trd, the detection switchingelement Trs, a reflection layer 84, a self-light emitting layer 81, anupper electrode 82, and a lower electrode 83. The planarization layer 59is provided on the detection switching element Trs, the conductive layerASL8, and the display switching element Trd, and the reflection layer 84is provided on the planarization layer 59. An insulating layer 86 isprovided on the reflection layer 84, and the lower electrode 83 and aninsulating layer 87 are provided on the insulating layer 86. Theself-light emitting layer 81 is provided on the lower electrode 83 andthe insulating layer 87, and the upper electrode 82 is provided on theself-light emitting layer 81. An insulating layer 88, an insulatinglayer 89, the color filter 32, and the second substrate 22 are laminatedon the upper electrode 82 in this order. FIG. 30 illustrates thesectional structure of the above-mentioned one subpixel SPix, and thesubpixels SPix including the self-light emitting layer 81 are arranged.

The lower electrode 83 is electrically coupled to the drain electrode 73of the display switching element Trd via a contact hole H9. The lowerelectrode 83 is provided to correspond to each subpixel SPix, and is aconductor serving as an anode of the organic light-emitting diode. Thelower electrode 83 is a translucent electrode that uses a translucentconductive material such as ITO. The self-light emitting layer 81includes an organic material, and includes a hole injection layer, ahole transport layer, a light emitting layer, an electron transportlayer, and an electron injection layer (not illustrated). The upperelectrode 82 is a conductor serving as a cathode of the organiclight-emitting diode. The upper electrode 82 is a translucent electrodethat uses a translucent conductive material such as ITO. Without beinglimited thereto, the translucent conductive material used for the upperelectrode 82 may be a conductive material having a different compositionsuch as indium zinc oxide (IZO). Alternatively a thin film metal layerthat is formed to be extremely thin to have light transmissivity may beemployed for the upper electrode 82. The reflection layer 84 is providedbelow the self-light emitting layer 81, and is formed of a metallicglossy material that reflects light from the self-light emitting layer81, such as silver, aluminum, and gold. The insulating layer 87 is aninsulating layer called dam, for partitioning the subpixels SPix. Theinsulating layer 88 is a sealing layer for sealing the upper electrode82, and a silicon oxide or a silicon nitride can be used. The insulatinglayer 89 is a planarization layer for inhibiting a step generated by theinsulating layer 87, and a silicon oxide, a silicon nitride or the likecan be used as the insulating layer 89.

With the configuration described above, light from the self-lightemitting layer 81 is transmitted through the color filter 32 and exitsfrom the first surface 22 a of the second substrate 22 to reach the eyesof an observer. The lighting amount of the self-light emitting layer 81is controlled for each subpixel SPix, and an image is displayed on thefirst surface 22 a of the second substrate 22 serving as the displaysurface.

Without being limited to the above-mentioned example, the lowerelectrode 83 may be a cathode and the upper electrode 82 may be ananode. In this case, the polarity of the display switching element Trdelectrically coupled to the lower electrode 83 can be changed asappropriate, and the lamination order of the carrier injection layers(hole injection layer and electron injection layer), the carriertransport layers (hole transport layer and electron transport layer),and the light emitting layer can be changed as appropriate.

Also in the seventh embodiment, the detection electrode 25 is providedon the first surface 21Aa of the first substrate 21A, and the detectionelectrode 25 is electrically coupled to the drain electrode 63 of thedetection switching element Trs. Thus, a fingerprint of a finger incontact with the second surface 21Ab of the first substrate 21A can bedetected on the basis of an electrostatic capacitance change in thedetection electrode 25. Specifically, the second surface 21Ab of thefirst substrate 21A functions as the detection surface of thefingerprint detection unit 30, and the first surface 22 a of the secondsubstrate 22, which is located on the opposite side of the detectionsurface across the detection electrode 25, functions as the displaysurface of the display panel 20.

FIG. 31 is a sectional view illustrating a sectional structure of adisplay device according to a modification of the seventh embodiment. Asillustrated in FIG. 31, in a display device 2B according to the presentmodification, a self-light emitting layer 81A is provided on the lowerelectrode 83, and an upper electrode 82A is provided on the self-lightemitting layer 81. The second substrate 22 is provided above the upperelectrode 82A with a sealing layer 88A interposed therebetween. In thepresent modification, the color filter 32 illustrated in FIG. 30 is notprovided.

The self-light emitting layers 81A are formed of light emittingmaterials that are different depending on the subpixels SPix, anddisplay light of colors of red (R), green (G), and blue (B). Theself-light emitting layer 81A for displaying red (R) is provided tocorrespond to the subpixel SPix for displaying red (R). The self-lightemitting layer 81A for displaying green (G) is provided to correspond tothe subpixel SPix for displaying green (G). The self-light emittinglayer 81A for displaying blue (B) is provided to correspond to thesubpixel SPix for displaying blue (B). In this manner, color display ofthe display device 2B can be implemented.

Also in the display device 2B according to the present modification, theconfigurations of the detection electrode 25, the detection switchingelement Trs, the display switching element Trd, and various kinds ofwire coupled thereto are the same as in the display device 2A in FIG.30. Thus, a fingerprint of a finger in contact with the second surface21Ab of the first substrate 21A can be detected.

Eighth Embodiment

FIG. 32 is a schematic sectional view schematically illustrating asectional structure of a fingerprint detection device according to aneighth embodiment. As illustrated in FIG. 32, a fingerprint detectiondevice 1A includes a first substrate 21A, first detection electrodes 26,and second detection electrodes 27. The first substrate 21A has a firstsurface 21Aa and a second surface 21Ab on the opposite side of the firstsurface 21Aa. The first detection electrodes 26 are provided on thefirst surface 21Aa of the first substrate 21A, and the second detectionelectrodes 27 are provided above the first detection electrodes 26 witha planarization layer 59 interposed therebetween. A protective layer 57for protecting the second detection electrodes 27 may be provided on thesecond detection electrodes 27.

The first detection electrodes 26 are detection electrodes for detectinga fingerprint of a finger in contact with the second surface 21Ab. Thesecond detection electrodes 27 are detection electrodes for detecting afingerprint of a finger in contact with another detection surface Sprovided on the first surface 21Aa side. The fingerprint detectiondevice 1A in the eighth embodiment is capable of detecting fingerprintson both of the first surface 21Aa and the second surface 21Ab of thefirst substrate 21A.

Next, the configurations of the first detection electrode 26 and thesecond detection electrode 27 are described with reference to FIG. 33 toFIG. 36. FIG. 33 is a plan view illustrating the planar structure of thefingerprint detection device according to the eighth embodiment. FIG. 34is an enlarged plan view of the first detection electrode and the seconddetection electrode. FIG. 35 is a sectional view taken along the lineXXXV-XXXV′ in FIG. 34. FIG. 36 is a sectional view taken along the lineXXXVI-XXXVI′ in FIG. 34.

As illustrated in FIG. 33, a first detection gate line GCLs1 is providedalong the row direction, and the first detection gate lines GCLs1 arearranged with intervals in the column direction. A first detection dataline SGLs1 is provided along the column direction, and the firstdetection data lines SGLs1 are arranged with intervals in the rowdirection. A second detection gate line GCLs2 is provided in parallel tothe first detection gate line GCLs1 and provided along the rowdirection, and the second detection gate lines GCLs2 are arranged withintervals in the column direction. A second detection data line SGLs2 isprovided in parallel to the first detection data line SGLs1 and providedalong the column direction, and the second detection data lines SGLs2are arranged with intervals in the row direction. The first detectionelectrode 26 and the second detection electrode 27 are arranged in aregion surrounded by the first detection gate line GCLs1, the firstdetection data line SGLs1, the second detection gate line GCLs2, and thesecond detection data line SGLs2. The first detection electrode 26 andthe second detection electrode 27 each have a substantially rectangularshape and are provided to overlap with each other. The overlapping firstdetection electrodes 26 and second detection electrodes 27 are arrangedin a matrix pattern.

A first detection switching element Trs1 is provided near the positionat which the first detection gate line GCLs1 and the first detectiondata line SGLs1 intersect with each other. The first detection switchingelement Trs1 is provided at the position corresponding to one firstdetection electrode 26.

A second detection switching element Trs2 is provided near the positionat which the second detection gate line GCLs2 and the second detectiondata line SGLs2 intersect with each other. The second detectionswitching element Trs2 is provided at the position corresponding to onesecond detection electrode 27.

The first detection switching element Trs1 and the second detectionswitching element Trs2 are formed of thin film transistors. In thepresent example, the first detection switching element Trs1 and thesecond detection switching element Trs2 are formed of n-channel MOS TFTelements.

In the fingerprint detection device 1A, similarly to the fingerprintdetection unit 30 illustrated in FIG. 1, a gate driver (not illustrated)for supplying the scanning signal Vscan to each of the first detectiongate line GCLs1 and the second detection gate line GCLs2 and a detectionelectrode driver (not illustrated) for supplying the drive signal Vf toeach of the first detection data line SGLs1 and the second detectiondata line SGLs2 are provided. Similarly to the detection unit 40illustrated in FIG. 2, detection signals from the first detectionelectrode 26 and the second detection electrode 27 are supplied to thedetection unit. The scanning signals Vscan may be supplied from a singlegate driver. Two gate drivers, specifically, a gate driver for supplyinga scanning signal Vscan1 to the first detection gate line GCLs1 and agate driver for supplying a scanning signal Vscan2 to the seconddetection gate line GCLs2 may be provided. Also for the detectionelectrode driver, the drive signal Vf may be supplied from a singledetection electrode driver, or the drive signal Vf may be supplied fromeach of two detection electrode drivers.

The gate driver sequentially selects the first detection gate linesGCLs1. The gate driver supplies the scanning signal Vscan to the firstdetection switching elements Trs1 through the selected first detectiongate line GCLs1. In this manner, the gate driver selects one line (onehorizontal line) of the first detection electrodes 26 as a firstdetection electrode block 26A to be detected. The first detectionelectrode block 26A includes a plurality of first detection electrodes26 arranged in the row direction. The detection electrode driver (notillustrated) supplies the drive signal Vf to each first detectionelectrode 26 in the first detection electrode block 26A through thefirst detection data line SGLs1. In this manner, a detection signal isoutput to the detection unit (not illustrated) through the firstdetection data line SGLs1 in accordance with an electrostaticcapacitance change in the first detection electrode 26.

Similarly, the gate driver sequentially selects the second detectiongate lines GCLs2. The gate driver supplies the scanning signal Vscan tothe second detection switching elements Trs2 through the selected seconddetection gate line GCLs2. In this manner, the gate driver selects oneline (one horizontal line) of the second detection electrodes 27 as asecond detection electrode block 27A to be detected. The seconddetection electrode block 27A includes a plurality of second detectionelectrodes 27 arranged in the row direction. The detection electrodedriver (not illustrated) supplies the drive signal Vf to each seconddetection electrode 27 in the second detection electrode block 27Athrough the second detection data line SGLs2. In this manner, adetection signal is output to the detection unit (not illustrated)through the second detection data line SGLs2 in accordance with anelectrostatic capacitance change in the second detection electrode 27.In this manner, a fingerprint of a finger in contact or in proximity isdetected in accordance with the fundamental principle ofself-capacitance fingerprint detection described above. The firstdetection electrode 26 and the second detection electrode 27 eachcorrespond to the detection electrode E1 in the fundamental principle ofself-capacitance fingerprint detection described above.

As illustrated in FIG. 34, the fifth wire ASL5 is provided to overlapwith the first detection gate line GCLs1 along the first detection gateline GCLs1. The sixth wire ASL6 is provided to overlap with the seconddetection gate line GCLs2 along the second detection gate line GCLs2.The fifth wire ASL5 and the sixth wire ASL6 are provided to becontinuous correspondingly to the first detection electrodes 26 andsecond detection electrodes 27 arranged in the row direction.

As illustrated in FIG. 34, the first detection electrode 26 has an areasmaller than that of the second detection electrode 27. The seconddetection electrode 27 protrudes to a position that does not overlapwith the first detection electrode 26, and covers the entire surface ofthe first detection electrode 26 except for a connection portion of thefirst detection electrode 26 and the first detection switching elementTrs1. The second detection electrode 27 is provided to further overlapwith the seventh wire ASL7, the conductive layer ASL8, and a conductivelayer ASL9. The seventh wire ASL7 is provided to surround the peripheryof the first detection electrode 26. The conductive layer ASL8 overlapswith the entire surfaces of the first detection electrode 26 and theseventh wire ASL7 except for a connection portion with the firstdetection switching element Trs1. The conductive layer ASL9 is providedcontinuously so as to overlap with the first detection electrodes 26 andthe second detection electrodes 27 arranged in a matrix pattern.

In the eighth embodiment, the detection electrode driver supplies thefifth wire ASL5, the sixth wire ASL6, the seventh wire ASL7, and theconductive layer ASL8 with the signal Vsg1 that is synchronized with thedrive signal Vf and has the same waveform as the drive signal Vf. Thus,the parasitic capacitances between the first detection gate line GCLs1and the first detection electrode 26 and between the second detectiongate line GCLs2 and the second detection electrode 27 are reduced tosuppress detection errors and the deterioration in detectionsensitivity. A drive circuit that is not provided in the detectionelectrode driver may be provided as appropriate to supply the signalVsg1. The conductive layer ASL8 is provided between the layer of thefirst detection electrode 26 and the layer of the second detectionelectrode 27, and hence capacitive coupling between the first detectionelectrode 26 and the second detection electrode 27 is suppressed tosuppress detection errors and the deterioration in detectionsensitivity. In this manner, the fingerprint detection operation basedon an electrostatic capacitance change in the first detection electrode26 and the fingerprint detection operation based on an electrostaticcapacitance change in the second detection electrode 27 can be performedindependently.

Next, the connection structure of the first detection electrode 26, thesecond detection electrode 27, each wire, and the conductive layers isdescribed. As illustrated in FIG. 35, the semiconductor layer 61 in thefirst detection switching element Trs1 is electrically coupled to thefirst detection data line SGLs1 via the contact hole H9. Thesemiconductor layer 61 is bent so as to intersect with the firstdetection gate line GCLs1 a plurality of times in a plan view. Thesemiconductor layer 61 is electrically coupled to the drain electrode 63via a contact hole H10. The drain electrode 63 intersects with theseventh wire ASL7 and extends to a position overlapping with the firstdetection electrode 26, and is electrically coupled to the firstdetection electrode 26 via a contact hole H11. In this manner, the firstdetection electrode 26 is electrically coupled to the first detectiondata line SGLs1 through the first detection switching element Trs1.

As illustrated in FIG. 35, the fifth wire ASL5 and the first detectionelectrode 26 are provided on the first surface 21Aa of the firstsubstrate 21A. The insulating layer 58 a is provided on the fifth wireASL5 and the first detection electrode 26. The semiconductor layer 61 isprovided on the insulating layer 58 a. The insulating layer 58 b isprovided on the semiconductor layer 61, and the first detection gateline GCLs1 and the seventh wire ASL7 are provided on the insulatinglayer 58 b. The insulating layer 58 c is provided on the first detectiongate line GCLs1 and the seventh wire ASL7, and the first detection dataline SGLs1, the drain electrode 63, and the conductive layer ASL8 areprovided on the insulating layer 58 c. The planarization layer 59 isprovided on the first detection data line SGLs1, the drain electrode 63,and the conductive layer ASL8, the conductive layer ASL9 is provided onthe planarization layer 59, and the second detection electrode 27 isprovided above the conductive layer ASL9 with an insulating layer 58 dinterposed therebetween. The protective layer 57 and a protective layer55 for protecting the second detection electrode 27 are provided on thesecond detection electrode 27. The top surface of the protective layer55 is the detection surface S.

As illustrated in FIG. 35, the fifth wire ASL5 is electrically coupledto the conductive layer ASL8 via a contact hole H12. Thus, when theabove-mentioned signal Vsg1 is supplied to the fifth wire ASL5, thesignal Vsg1 is supplied to the conductive layer ASL8 through the tabportion ASL5 a (refer to FIG. 34). The seventh wire ASL7 is coupled tothe conductive layer ASL8 via a contact hole H14, and the conductivelayer ASL9 is coupled to the conductive layer ASL8 via a contact holeH13. With this configuration, the signal Vsg1 supplied to the fifth wireASL5 is supplied to the seventh wire ASL7 and the conductive layer ASL9through the conductive layer ASL8.

As illustrated in FIG. 36, the semiconductor layer 71 in the seconddetection switching element Trs2 is electrically coupled to the seconddetection data line SGLs2 via a contact hole H15. The semiconductorlayer 71 is bent so as to intersect with the second detection gate lineGCLs2 a plurality of times in a plan view. The semiconductor layer 71 iselectrically coupled to the drain electrode 73 via a contact hole H16.As described above, the conductive layer ASL9 is provided continuouslyso as to overlap with the first detection electrodes 26 and the seconddetection electrodes 27 arranged in a matrix pattern. An opening ASL9 ais provided in the conductive layer ASL9, and the drain electrode 73 iselectrically coupled to the second detection electrode 27 via a contacthole H17 that passes through the opening ASL9 a. In this manner, thesecond detection electrode 27 is electrically coupled to the seconddetection data line SGLs2 through the second detection switching elementTrs2.

As illustrated in FIG. 36, the sixth wire ASL6 is provided on the firstsurface 21Aa of the substrate 21. The insulating layer 58 a is providedon the sixth wire ASL6, and the semiconductor layer 61 is provided onthe insulating layer 58 a. The insulating layer 58 b is provided on thesemiconductor layer 61, and the second detection gate line GCLs2 isprovided on the insulating layer 58 b. The insulating layer 58 c isprovided on the second detection gate line GCLs2, and the seconddetection data line SGLs2 and the drain electrode 73 are provided on theinsulating layer 58 c. The planarization layer 59 is provide on thesecond detection data line SGLs2 and the drain electrode 73, and thesecond detection electrode 27 is provided above the planarization layer59 with the conductive layer ASL9 and the insulating layer 58 dinterposed therebetween. The protective layer 57 for protecting thesecond detection electrode 27 is provided on the second detectionelectrode 27.

As illustrated in FIG. 35 and FIG. 36, the first detection switchingelement Trs1 and the second detection switching element Trs2 areprovided in the same layer. Without being limited thereto, the firstdetection switching element Trs1 and the second detection switchingelement Trs2 may be provided in different layers. The conductive layerASL9 is disposed between the first detection electrode 26 and the seconddetection electrode 27, and is provided continuously so as to overlapwith the second detection electrodes 27 arranged in the row directionand the column direction.

Next, a drive method for the fingerprint detection device 1A accordingto the eighth embodiment is described. FIG. 37 is a timing waveformdiagram illustrating an operation example of the fingerprint detectiondevice according to the eighth embodiment. As illustrated in FIG. 37,detection periods Pt1, Pt2, Pt3, and Pt4 during which the fingerprintdetection operation is performed are arranged in a time division manner.

As illustrated in FIG. 37, in the detection period Pt1, the firstdetection gate line GCLs1(n) in the n-th row (refer to FIG. 33) isselected, and the scanning signal Vscan1(n) is turned on (High level).First detection switching elements Trs1 corresponding to the firstdetection electrode block 26A(n) in the n-th row are turned on (open).Accordingly, the drive signal Vf is supplied to the respective firstdetection electrodes 26 in the first detection electrode block 26A(n)through the first detection data lines SGLs1(m), SGLs1(m+1), andSGLs1(m+2). The detection signal Vdet is output to the detection unitfrom each first detection electrode 26 in the first detection electrodeblock 26A(n) on the basis of the fundamental principle ofself-capacitance fingerprint detection described above. In this manner,a fingerprint of a finger in contact with the second surface 21Ab of thefirst substrate 21A can be detected.

In the detection period Pt1, a first detection electrode block 26A(n+1),a second detection electrode block 27A(n), and a second detectionelectrode block 27A(n+1) that are not selected as detection targets arein the floating state in which a fixed potential is not supplied. Thus,parasitic capacitances between the first detection electrode block26A(n) selected as a detection target and the first detection electrodeblock 26A(n+1), the second detection electrode block 27A(n), and thesecond detection electrode block 27A(n+1) that are not selected asdetection targets can be suppressed.

Next, in the detection period Pt2, the second detection gate lineGCLs2(n) in the n-th row is selected, and the scanning signal Vscan2(n)is turned on (High level). Second detection switching elements Trs2 inthe second detection electrode block 27A(n) in the n-th row are turnedon (open). Accordingly, the drive signal Vf is supplied to therespective second detection electrodes 27 in the second detectionelectrode block 27A(n) through the second detection data lines SGLs2(m),SGLs2(m+1), and SGLs2(m+2), and the detection signal Vdet is output tothe detection unit from each second detection electrode 27 in the seconddetection electrode block 27A(n). In this manner, a fingerprint of afinger in contact with the detection surface S on the first surface 21Aaside of the first substrate 21A can be detected.

In the detection period Pt2, the first detection electrode blocks 26A(n)and 26A(n+1) and the second detection electrode block 27A(n+1) are inthe floating state in which a fixed potential is not supplied.

In the detection period Pt3, the first detection gate line GCLs1(n+1) inthe (n+1)th row is selected, and the scanning signal Vscan1(n+1) isturned on (High level). First detection switching elements Trs1corresponding to the first detection electrode block 26A(n+1) in the(n+1)th row are turned on (open). Accordingly, the drive signal Vf issupplied to the respective first detection electrodes 26 in the firstdetection electrode block 26A(n+1) through the first detection datalines SGLs1(m), SGLs1(m+1), and SGLs1(m+2). The detection signal Vdet isoutput to the detection unit from each first detection electrode 26 inthe first detection electrode block 26A(n+1) on the basis of thefundamental principle of self-capacitance fingerprint detectiondescribed above. In this manner, a fingerprint of a finger in contactwith the second surface 21Ab of the first substrate 21A can be detected.

Next, in the detection period Pt4, the second detection gate lineGCLs2(n+1) in the (n+1)th row is selected, and the scanning signalVscan2(n+1) is turned on (High level). Second detection switchingelements Trs2 in the second detection electrode block 27A(n+1) in the(n+1) row are turned on (open). Accordingly, the drive signal Vf issupplied to the respective second detection electrodes 27 in the seconddetection electrode block 27A(n+1) through the second detection datalines SGLs2(m), SGLs2(m+1), and SGLs2(m+2), and the detection signalVdet is output to the detection unit from each second detectionelectrode 27 in the second detection electrode block 27A(n+1). In thismanner, a fingerprint of a finger in contact or in proximity on thefirst surface 21Aa side of the first substrate 21A can be detected. Thisoperation is sequentially repeated to carry out the fingerprintdetection operation on the entire one detection surface S on the firstsurface 21Aa side of the first substrate 21A and on the entire otherdetection surface that is the second surface 21Ab.

In the detection periods Pt1 to Pt4, the fifth wire ASL5, the sixth wireASL6, the seventh wire ASL7, the conductive layer ASL8, and theconductive layer ASL9 are supplied with the signal Vsg1. Thus, theparasitic capacitances between each detection electrode in the detectionelectrode block selected as a detection target and the first detectiongate line GCLs1, the second detection gate line GCLs2, and the like aresuppressed to suppress the deterioration in detection sensitivity.

In the eighth embodiment, in the detection periods Pt1 and Pt3, afingerprint of a finger in contact or in proximity on the second surface21Ab side of the first substrate 21A is detected on the basis of anelectrostatic capacitance change in the first detection electrode 26. Inthe detection periods Pt2 and Pt4, a fingerprint of a finger in contactor in proximity on the first surface 21Aa side of the first substrate21A is detected on the basis of an electrostatic capacitance change inthe second detection electrode 27. In this manner, the fingerprintdetection on the first surface 21Aa side of the first substrate 21A andthe fingerprint detection on the second surface 21Ab side arealternatingly performed in a time division manner, but the configurationis not limited thereto. For example, after the fingerprint detection onthe first surface 21Aa side of the first substrate 21A is performedcontinuously in a plurality of periods, the fingerprint detection on thesecond surface 21Ab side of the first substrate 21A may be performedcontinuously in a plurality of periods. The fingerprint detection on thefirst surface 21Aa side of the first substrate 21A and the fingerprintdetection on the second surface 21Ab side may be performed in the sameperiod.

First Modification

The fingerprint detection device 1A is not limited to the configurationillustrated in FIG. 34. FIG. 38 is an enlarged plan view of a firstdetection electrode and a second detection electrode in a fingerprintdetection device according to a first modification of the eighthembodiment.

As illustrated in FIG. 38, in the first modification, a first detectionswitching element Trs1 and a second detection switching element Trs2 areprovided correspondingly to one detection data line SGLs. The firstdetection switching element Trs1 is provided at an intersection partbetween the detection data line SGLs and a first detection gate lineGCLs1, and the second detection switching element Trs2 is provided at anintersection part between the detection data line SGLs and a seconddetection gate line GCLs2. In this manner, the first detection electrode26 and the second detection electrode 27 are supplied with the drivesignal Vf through the common detection data line SGLs.

In this case, similarly to the drive method illustrated in FIG. 37, thefirst detection switching element Trs1 and the second detectionswitching element Trs2 are switched between on and off by scanningsignals Vscan1 and Vscan2, respectively. Consequently, the fingerprintdetection on the first surface 21Aa side of the first substrate 21A andthe fingerprint detection on the second surface 21Ab side can bealternatingly performed in a time division manner. By setting the firstdetection switching element Trs1 and the second detection switchingelement Trs2 to the on state in the same period, the same drive signalVf is supplied to the first detection electrode 26 and the seconddetection electrode 27. In this manner, the fingerprint detection on thefirst surface 21Aa side of the first substrate 21A and the fingerprintdetection on the second surface 21Ab side can be simultaneouslyperformed in the same period.

Second Modification

FIG. 39 is an enlarged plan view of a first detection electrode and asecond detection electrode in a fingerprint detection device accordingto a second modification of the eighth embodiment. As illustrated inFIG. 39, in the second modification, a first detection switching elementTrs1 and a second detection switching element Trs2 are provided tocorrespond to one detection gate line GCLs. The first detectionswitching element Trs1 is provided at an intersection part between thedetection gate line GCLs and a first detection data line SGLs1, and thesecond detection switching element Trs2 is provided at an intersectionpart between the detection gate line GCLs and a second detection dataline SGLs2. In this manner, the first detection switching element Trs1and the second detection switching element Trs2 are supplied with thescanning signal Vscan through the common detection gate line GCLs.

In this case, the first detection switching element Trs1 and the seconddetection switching element Trs2 are switched between on and off by thesame scanning signal Vscan. Thus, the first detection electrode 26 issupplied with the drive signal Vf through the first detection data lineSGLs1 and the second detection electrode 27 is supplied with the drivesignal Vf through the second detection data line SGLs2 at the same timein the same detection period. Consequently, in the second modification,the fingerprint detection on one detection surface S on the firstsurface 21Aa side and the fingerprint detection on the other detectionsurface as the second surface 21Ab are simultaneously performed in thesame period.

Ninth Embodiment

FIG. 40 is a schematic sectional view schematically illustrating asectional structure of a display apparatus according to a ninthembodiment. FIG. 41 is a perspective view of the display apparatusaccording to the ninth embodiment, for describing the state in whichfingerprint detection operation is performed.

A display apparatus 3 in the ninth embodiment includes a display device2 and a fingerprint detection device 1A. The display device 2 is adisplay device described in the fifth embodiment to the seventhembodiment, and the fingerprint detection device 1A is a fingerprintdetection device described in the eighth embodiment. For example, thedisplay apparatus 3 in the ninth embodiment can be used as a card-typemultifunctional display apparatus as illustrated in FIG. 41. Asillustrated in FIG. 40, the display device 2 and the fingerprintdetection device 1A include a common first substrate 121. As the firstsubstrate 121, for example, a flexible substrate including a film base121A and a resin layer 121B provided on the film base 121A can be used.

As illustrated in FIG. 40, the top surface of the resin layer 121B is afirst surface 121 a of the first substrate 121, and the bottom surfaceof the film base 121A is a second surface 121 b of the first substrate121. A second substrate 122 is provided on the first surface 121 a sideof the first substrate 121. Detection electrodes 125 in the displaydevice 2 are provided on the first surface 121 a of the first substrate121 at positions overlapping with the second substrate 122. Firstdetection electrodes 126 in the fingerprint detection device 1A areprovided on the first surface 121 a of the first substrate 121 atpositions not overlapping with the second substrate 122. An insulatinglayer 158 and a planarization layer 159 are laminated in this order onthe detection electrode 125 and the first detection electrode 126.Reflection electrodes 128 in the display device 2 are provided on theplanarization layer 159 at positions overlapping with the secondsubstrate 122. Second detection electrodes 127 in the fingerprintdetection device 1A are provided on the planarization layer 159 atpositions not overlapping with the second substrate 122.

The configuration described above enables the display device 2 todisplay an image on a first surface 122 a of the second substrate 122and to detect a fingerprint of a finger in contact or in proximity onthe second surface 121 b side of the first substrate 121. Theconfiguration described above enables the fingerprint detection device1A to detect a fingerprint of a finger in contact or in proximity on thefirst surface 121 a side of the first substrate 121 and to detect afingerprint of a finger in contact or in proximity on the second surface121 b side of the first substrate 121.

The display apparatus 3 includes a control IC 19A and a communication IC19B that are provided on the planarization layer 159 of the firstsubstrate 121. The control IC 19A controls the display operation and thefingerprint detection operation of the display device 2 and thefingerprint detection operation of the fingerprint detection device 1A.The communication IC 19B is provided to perform wireless communicationwith an external reader/writer through a coil 129 provided on the firstsubstrate 121, for example.

As illustrated in FIG. 40, the display device 2 may be provided with atouch detection electrode TDL on a second surface 122 b side of thesecond substrate 122 to have a built-in touch detection function ofdetecting the position of a finger in contact or in proximity with thefirst surface 122 a of the second substrate 122. A protective layer 157for protecting the second detection electrodes 127, the control IC 19A,and the communication IC 19B may be provided above the first substrate121.

As illustrated in FIG. 41, the display apparatus 3 is a card-typeapparatus, and has, on one surface, a display region 10 a and afingerprint detection region 1Aa that is provided in a region 10 boutside the display region. On the other surface, fingerprints can bedetected in a region overlapping with the display region 10 a and in aregion overlapping with the fingerprint detection region 1Aa. Forexample, when the display apparatus 3 has an IC chip mounted thereon andhas the electronic money function or the function of storing personaldata therein, advanced security measures are required. Thus, thesecurity of the display apparatus 3 can be improved by simultaneouslyperforming fingerprint authentication using a plurality of fingers in amanner that the fingers are brought into contact with both surfaces ofthe display apparatus 3.

While the exemplary embodiments of the present invention have beendescribed, the present invention is not intended to be limited to theembodiments. What is disclosed in the embodiments is merely illustrativeand various kinds of changes can be made in the scope not departing fromthe gist of the present invention. It should be understood thatappropriate changes made in the scope not departing from the gist of thepresent invention pertain to the technical scope of the presentinvention.

For example, the gate line GCL and the data line SGL are orthogonal toeach other, but without being limited thereto, the gate line GCL and thedata line SGL may be provided to be inclined in the row direction or thecolumn direction. In this case, the shape of the detection electrode 25may be a shape other than a rectangle, such as a rhombic and aparallelogram. The drive method for the fingerprint detection device isillustrative, and for example, the signal Vsg1 may be supplied to adetection electrode other than a detection electrode to be detected.

What is claimed is:
 1. A fingerprint detection device, comprising: asubstrate having a first surface and a second surface on an oppositeside of the first surface, the first surface serving as a detectionsurface configured to detect an unevenness of a finger in contact or inproximity thereto; a detection electrode provided on a second surfaceside of the substrate and configured to be applied with a drive signalthat produces an electrostatic capacitance to detect the unevenness; aswitching element provided at a position corresponding to the detectionelectrode, the switching element comprising a semiconductor layer, agate electrode opposed to the semiconductor layer, a source electrode,and a drain electrode; a gate line configured to supply a scanningsignal to the gate electrode; and a first conductive wire configured tobe supplied with a signal synchronized with the drive signal, wherein,in a vertical direction perpendicular to the second surface, a firstdistance from the detection electrode to the second surface is equal toor less than a second distance from the semiconductor layer to thesecond surface, a third distance from the drain electrode to the secondsurface is equal to or greater than the second distance, the drainelectrode is in contact with the semiconductor layer through a firstcontact hole and in contact with the detection electrode through asecond contact hole, the gate line extends in a horizontal directionalong the second surface, the first conductive wire extends in thehorizontal direction between the gate line and the detection electrodein a plan view, and the gate electrode, the gate line, and the firstconductive layer are in a same layer.
 2. The fingerprint detectiondevice according to claim 1, further comprising a drive circuit providedon the second surface side of the substrate and configured to supply thedrive signal to the detection electrode, wherein the source electrode iselectrically connected to the drive circuit and in contact with thesemiconductor layer through a third contact hole.
 3. The fingerprintdetection device according to claim 1, wherein a fourth distance fromthe gate electrode to the second surface is greater than the seconddistance and is less than the third distance.
 4. The fingerprintdetection device according to claim 1, wherein the first conductive wireis provided to surround the detection electrode.
 5. The fingerprintdetection device according to claim 1, further comprising a secondconductive wire configured to be supplied with the signal, wherein thesecond conductive wire overlaps the gate line, and in the verticaldirection, the second distance is larger than a fifth distance from thesecond conductive wire to the second surface.
 6. The fingerprintdetection device according to claim 5, wherein the second conductivewire has a width larger than a width of the gate line.
 7. Thefingerprint detection device according to claim 1, further comprising asecond conductive wire configured to be supplied with the signal,wherein the second conductive wire overlaps the gate line, and thedetection electrode and the second conductive wire are in a same layer.8. The fingerprint detection device according to claim 7, wherein thesecond conductive wire has a width larger than a width of the gate line.9. The fingerprint detection device according to claim 1, furthercomprising a conductive layer that is opposed to the second surface suchthat the detection electrode is disposed between the second surface andthe conductive layer, wherein the conductive layer is supplied with thesignal synchronized with the drive signal.
 10. The fingerprint detectiondevice according to claim 9, wherein the conductive layer and the drainelectrode are in a same layer.
 11. The fingerprint detection deviceaccording to claim 1, further comprising a conductive layer that isopposed to the second surface such that the detection electrode isdisposed between the second surface and the conductive layer, whereinthe conductive layer is electrically connected to the first conductivewire.
 12. The fingerprint detection device according to claim 11,wherein the conductive layer and the drain electrode are in a samelayer.
 13. The fingerprint detection device according to claim 1,further comprising: a planarization layer provided on the second surfaceside to cover the detection electrode; and a protective layer includingan inorganic material on the planarization layer.
 14. The fingerprintdetective service according to claim 13, wherein the inorganic materialcomprises a translucent conductive material.
 15. The fingerprintdetection device according to claim 1, wherein the substrate is fixed toa casting, and the first surface is exposed from an opening provided inthe casing.